Pyrazine-4-carbamate or -urea derivatives as herbicides

ABSTRACT

The present invention relates to herbicidally active pyridyl-/pyrimidyl-pyrazine derivatives, as well as to processes and intermediates used for the preparation of such derivatives. The invention further extends to herbicidal compositions comprising such derivatives, as well as to the use of such compounds and compositions in controlling undesirable plant growth: in particular the use in controlling weeds, in crops of useful plants.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Stage application of InternationalApplication No. PCT/EP2018/075231 filed Sep. 18, 2018 which claimspriority to GB 1715414.7, filed Sep. 22, 2017, filed in the UnitedKingdom, the entire contents of which applications are herebyincorporated by reference.

The present invention relates to herbicidally activepyridyl-/pyrimidyl-pyrazine derivatives, as well as to processes andintermediates used for the preparation of such derivatives. Theinvention further extends to herbicidal compositions comprising suchderivatives, as well as to the use of such compounds and compositions incontrolling undesirable plant growth: in particular the use incontrolling weeds, in crops of useful plants.

Both WO2010/141275 and WO2010/071837 describe pyridyl-pyrazinecarboxylicacid derivatives for pharmaceutical use.

Certain pyridyl-pyrazine and pyrimidyl-pyrazine derivatives are knownfrom JP2015-147757, where they are stated to have activity asinsecticidal agents, and in particular acaricidal agents.

The present invention is based on the finding that pyridyl-pyrimidine,and pyrimidyl-pyrimidine, derivatives of Formula (I) as defined herein,exhibit surprisingly good herbicidal activity. Thus, according to thepresent invention there is provided a compound of Formula (I)

or a salt thereof, wherein,

X¹ is N or CR¹;

R¹ is selected from the group consisting of hydrogen, halogen, cyano,C₁-C₆alkyl, C₃-C₆cycloalkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₁-C₆alkoxy,—C(O)OC₁-C₆alkyl, —S(O)_(p)C₁-C₆alkyl, NR⁶R⁷, C₁-C₆haloalkoxy andC₁-C₆haloalkyl;

R² is selected from the group consisting of halogen, cyano, nitro,C₁-C₆alkyl, C₁-C₆haloalkyl, C₂-C₆alkenyl, C₂-C₆alkynyl,trimethylsilylC₂-C₆alkynyl-, C₃-C₆cycloalkyl, C₅-C₆cycloalkenyl,—C(O)OC₁-C₆alkyl, —S(O)_(p)(C₁-C₆alkyl), C₁-C₆alkoxy, C₁-C₆haloalkoxy,—(CR^(a)R^(b))_(q)R¹⁵, phenyl and benzyloxy;

R¹⁵ is hydroxy, —C(O)OR^(c), —OC(O)R^(c), —C₃-C₆cycloalkyl, or an -aryl,-aryloxy, -heteroaryl, -heteroaryloxy or -heterocyclyl ring, whereinsaid ring is optionally substituted by 1 to 3 independent R⁸;

R³ is —C(O)X²R¹²;

X² is O or NR¹⁰;

R⁴ is selected from the group consisting of hydrogen, C₁-C₆alkyl,C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy, C₃-C₆cycloalkyl,C₃-C₆alkenyl, C₃-C₆alkynyl, —C(O)R⁹—(CR^(a)R^(b))_(q)R⁵, —C(O)X³R¹³; or,

when X² is O, R¹² is selected from the group consisting of C₁-C₆alkyl,C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl, C_(r)alkoxyC_(s)haloalkyl,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹, or R⁴ and R¹² together with the heteroatoms towhich they are joined form a 5-7 membered ring system optionallycontaining 1 additional heteroatom selected from S, O and N, whereinwhen said additional heteroatom is sulphur it is in the form S(O)_(p).

when X² is NR¹⁰, R¹² is selected from the group consisting of hydrogen,C₁-C₆alkyl, C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹; or R¹⁰ and R¹² together with the nitrogen atom towhich they are both joined, can form a 5-, 6-, or 7-memberered ring,optionally containing 1 to 3 additional heteroatoms each independentlyselected from O, N or S, wherein when said ring contains a ring sulphur,said ring sulphur is in the form S(O)_(p); or R⁴ and R¹⁰ together withthe atoms to which they are joined form a 5-7 membered ring systemoptionally comprising from 1 or 2 additional heteroatoms independentlyselected from S, O and N and wherein when said ring system contains aring sulphur, said ring sulphur is in the form S(O)_(p); or,

R¹⁰ is independently selected from the group consisting of hydrogen,C₁-C₆alkyl, C₃-C₆ cycloalkyl;

when R⁴ is —C(O)X³R¹³, X³ is O or NR¹⁴;

when X³ is O, R¹³ is selected from the group consisting of C₁-C₆alkyl,C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl, C_(r)alkoxyC_(s)haloalkyl,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹, or R³ and R¹³ together with the heteroatoms towhich they are joined form a 5-7 membered ring system optionallycontaining 1 additional heteroatom selected from S, O and N, whereinwhen said additional heteroatom is sulphur it is in the form S(O)_(p).

when X³ is NR¹⁴, R¹³ is selected from the group consisting of hydrogen,C₁-C₆alkyl, C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹; or R¹⁴ and R¹³ together with the nitrogen atom towhich they are both joined, can form a 5-, 6-, or 7-memberered ring,optionally containing 1 or 2 additional heteroatoms each independentlyselected from O, N or S, wherein when said ring contains a ring sulphur,said ring sulphur is in the form S(O)_(p;)

R^(a) is hydrogen or C₁-C₂ alkyl;

R^(b) is hydrogen or C₁-C₂ alkyl;

R^(c) is hydrogen or C₁-C₄alkyl;

R⁵ is cyano, —C(O)OC₁-C₆alkyl, —C₃-C₆cycloalkyl, -aryl or -heteroarylwherein said aryl and heteroaryl are optionally substituted by 1 to 3independent R⁸;

R⁶ and R⁷ are independently selected from the group consisting ofhydrogen, C₁-C₆alkyl, and —C(O)OC₁-C₄alkyl;

each R⁸ is independently selected from the group consisting of halogen,C₁-C₆alkyl and C₁-C₆alkoxy-, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy-, cyanoand S(O)_(p)(C₁-C₆alkyl);

R⁹ is selected from the group consisting of hydrogen, C₁-C₆alkyl,C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy, C₂-C₆alkenyl,C₂-C₆alkynyl, and —(CR^(a)R^(b))_(q)R¹¹;

R¹¹ is cyano, —C₃-C₆cycloalkyl, or an -aryl, -heteroaryl or-heterocyclyl ring, wherein said ring is optionally substituted by 1 to3 independent R⁸, and wherein when said ring contains a ring sulphur,said ring sulphur is in the form S(O)_(p);

n is 0 or 1;

p is 0, 1, or 2;

q is 0, 1, 2, 3, 4, 5 or 6;

r is 1, 2, 3, 4, or 5, s is 1, 2, 3, 4, or 5, and the sum of r+s is lessthan or equal to 6.

Compounds of formula (I) may exist as different geometric isomers, or indifferent tautomeric forms. This invention covers the use of all suchisomers and tautomers, and mixtures thereof in all proportions, as wellas isotopic forms such as deuterated compounds.

It may be the case that compounds of formula (I) may contain one or moreasymmetric centers and may thus give rise to optical isomers anddiastereomers. While shown without respect to stereochemistry, thepresent invention includes the use of all such optical isomers anddiastereomers as well as the racemic and resolved, enantiomerically pureR and S stereoisomers and other mixtures of the R and S stereoisomersand agrochemically acceptable salts thereof.

Each alkyl moiety either alone or as part of a larger group (such asalkoxy, alkylthio, alkoxycarbonyl, alkylcarbonyl, alkylaminocarbonyl, ordialkylaminocarbonyl, et al.) may be straight-chained or branched.Typically, the alkyl is, for example, methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl,neopentyl, or n-hexyl. The alkyl groups are generally C₁-C₆ alkyl groups(except where already defined more narrowly), but are preferably C₁-C₄alkyl or C₁-C₃ alkyl groups, and, more preferably, are C1-C2 alkylgroups (such as methyl).

Alkenyl and alkynyl moieties can be in the form of straight or branchedchains, and the alkenyl moieties, where appropriate, can be of eitherthe (E)- or (Z)-configuration. Alkenyl and alkynyl moieties can containone or more double and/or triple bonds in any combination; butpreferably contain only one double bond (for alkenyl) or only one triplebond (for alkynyl).

The alkenyl or alkynyl moieties are typically C₂-C₄ alkenyl or C₂-C₄alkynyl, more specifically ethenyl (vinyl), prop-2-enyl, prop-3-enyl(allyl), ethynyl, prop-3-ynyl (propargyl), or prop-1-ynyl. Preferably,the term cycloalkyl refers to cyclopropyl, cyclobutyl, cyclopentyl orcyclohexyl.

In the context of the present specification the term “aryl” preferablymeans phenyl. Heteroaryl groups and heteroaryl rings (either alone or aspart of a larger group, such as heteroaryl-alkyl-) are ring systemscontaining at least one heteroatom and can be in mono- or bi-cyclicform. Typically “heteroaryl” is as used in the context of this inventionincludes furyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl,oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, pyridyl,pyrimidinyl, pyridazinyl, pyrazinyl, and triazinyl rings, which may ormay not be substituted as described herein.

The term “heterocyclyl” as used herein, encompasses ring systemscontaining at least one heteroatom and that are typically in monocyclicform. Preferably, heterocyclyl groups will contain up to two heteroatomswhich will preferably be chosen from nitrogen, oxygen and sulfur. Wherea heterocycle contains sulfur as a heteroatom it may be in oxidized formi.e. in the form —S(O)_(p)— where p is an integer of 0, 1 or 2 asdefined herein. Such heterocyclyl groups are preferably 3- to8-membered, and more preferably 3- to 6-membered rings. Examples ofheterocyclic groups include oxetanyl, thietanyl, and azetidinyl groups.Such heterocyclyl rings may or may not be substituted as describedherein.

Halogen (or halo) encompasses fluorine, chlorine, bromine or iodine. Thesame correspondingly applies to halogen in the context of otherdefinitions, such as haloalkyl or halophenyl.

Haloalkyl groups having a chain length of from 1 to 6 carbon atoms are,for example, fluoromethyl, difluoromethyl, trifluoromethyl,chloromethyl, dichloromethyl, trichloromethyl, 2,2,2-trifluoroethyl,2-fluoroethyl, 2-chloroethyl, pentafluoroethyl,1,1-difluoro-2,2,2-trichloroethyl, 2,2,3,3-tetrafluoroethyl and2,2,2-trichloroethyl, heptafluoro-n-propyl and perfluoro-n-hexyl.

Alkoxy groups preferably have a chain length of from 1 to 6 carbonatoms. Alkoxy is, for example, methoxy, ethoxy, propoxy, isopropoxy,n-butoxy, isobutoxy, sec-butoxy or tert-butoxy or a pentyloxy orhexyloxy isomer, preferably methoxy and ethoxy. It should also beappreciated that two alkoxy substituents may be present on the samecarbon atom.

Haloalkoxy is, for example, fluoromethoxy, difluoromethoxy,trifluoromethoxy, 2,2,2-trifluoroethoxy, 1,1,2,2-tetrafluoroethoxy,2-fluoroethoxy, 2-chloroethoxy, 2,2-difluoroethoxy or2,2,2-trichloroethoxy, preferably difluoromethoxy, 2-chloroethoxy ortrifluoromethoxy.

C₁-C₆ alkyl-S-(alkylthio) is, for example, methylthio, ethylthio,propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio ortert-butylthio, preferably methylthio or ethylthio.

C₁-C₆ alkyl-S(O)-(alkylsulfinyl) is, for example, methylsulfinyl,ethylsulfinyl, propylsulfinyl, isopropylsulfinyl, n-butylsulfinyl,isobutylsulfinyl, sec-butylsulfinyl or tert-butylsulfinyl, preferablymethylsulfinyl or ethylsulfinyl.

C₁-C₆ alkyl-S(O)₂-(alkylsulfonyl) is, for example, methylsulfonyl,ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, n-butylsulfonyl,isobutylsulfonyl, sec-butylsulfonyl or tert-butylsulfonyl, preferablymethylsulfonyl or ethylsulfonyl.

Compounds of formula (I) may form, and/or be used as, agronomicallyacceptable salts with amines (for example ammonia, dimethylamine andtriethylamine), alkali metal and alkaline earth metal bases orquaternary ammonium bases. Among the alkali metal and alkaline earthmetal hydroxides, oxides, alkoxides and hydrogen carbonates andcarbonates used in salt formation, emphasis is to be given to thehydroxides, alkoxides, oxides and carbonates of lithium, sodium,potassium, magnesium and calcium, but especially those of sodium,magnesium and calcium. The corresponding trimethylsulfonium salt mayalso be used.

Compounds of formula (I) may also form (and/or be used as) agronomicallyacceptable salts with various organic and/or inorganic acids, forexample, acetic, propionic, lactic, citric, tartaric, succinic, fumaric,maleic, malonic, mandelic, malic, phthalic, hydrochloric, hydrobromic,phosphoric, nitric, sulfuric, methanesulfonic, naphthalenesulfonic,benzenesulfonic, toluenesulfonic, camphorsulfonic, and similarly knownacceptable acids, when the compound of formula (I) contains a basicmoiety.

Where appropriate compounds of formula (I) may also be in the formof/used as an N-oxide.

Compounds of formula (I) may also be in the form of/used as hydrateswhich may be formed during the salt formation.

Preferred values of X¹, X², X³, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰,R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R^(a), R^(b), R^(c) n, p, q, r and s are as setout below, and a compound of formula (I) according to the invention maycomprise any combination of said values. The skilled person willappreciate that values for any specified set of embodiments may combinedwith values for any other set of embodiments where such combinations arenot mutually exclusive.

The skilled man will also appreciate that the values or r and s in thedefinitions C_(r)alkoxyC_(s)alkyl and C_(r)alkoxyC_(s)haloalkyl are suchthat the length of the carbon chain within the substituent does notexceed 6. Preferred values of r are 1, 2, or 3. Preferred values for sare 1, 2, or 3. In various embodiments r is 1, s is 1; or, r is 1, s is2; or r is 1, s is 3; or r is 2, s is 1; r is 2, s is 2; or r is 2, s is3; or r is 3, s is 1; or r is 3, s is 2, r is 3, s is 3. Particularlypreferred substituents thus include methoxymethyl, and ethoxymethyl.

In one particular embodiment of the present invention, X¹ is N.

In another embodiment of the present invention, X¹ is CR¹ and R¹ ispreferably selected from the group consisting of cyano, halogen,C₁-C₆alkoxy, C₁-C₆haloalkoxy, C₁-C₆haloalkyl, and —S(O)_(p)C₁-C₆alkyl.More preferably R¹ is selected from the group consisting of cyano,fluoro, chloro, methoxy, difluoromethoxy, trifluoromethyl andthiomethyl. More preferably still, R¹ is selected from the groupconsisting of cyano, fluoro, chloro, methoxy, trifluoromethyl andthiomethyl. Even more preferably still, R¹ is cyano, fluoro, orthiomethyl.

Preferably R² is selected from the group consisting of halogen, cyano,C₁-C₄alkyl, C₃-C₆cycloalkyl, C₁-C₄alkoxy, C₁-C₄haloalkyl,C₁-C₄thioalkyl, C₂-C₄alkenyl, C₅-C₆cycloalkenyl, C₂-C₄alkynyl,trimethylsilylC₂-C₄alkynyl-, —C(O)OC₁-C₄alkyl, —(CR^(a)R^(b))_(q)R¹⁵,phenyl, and benzyloxy. More preferably R² is halogen, cyano, C₁-C₃alkyl,cylcopropyl, C₁-C₂alkoxy, C₁-C₂haloalkyl, C₁-C₂thioalkyl, C₂-C₄alkenyl,C₅-C₆cycloalkenyl, acetylene, trimethylsilylacetylene-,—C(O)OC₁-C₄alkyl, —CH₂OH, and -benzyloxy.

Where X² is O (i.e. where R³ is —C(O)OR¹²), R¹² is preferably selectedfrom the group consisting of hydrogen, C₁-C₆alkyl,C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl, C_(r)alkoxyC_(s)haloalkyl,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹. In such embodiments, R¹² is preferablyC₁-C₄alkyl, C₁-C₄ haloalkyl, C₁-C₃alkoxyC₁-C₃alkyl,C₁-C₃alkylthioC₁-C₃alkyl, or CR^(a)R^(b) _(q)R¹¹, wherein q is 0, 1 or2, R^(a) and R^(b) are each hydrogen, and R¹¹ is cyano, C₃-C₆cycloalkyl,a 5- or 6-membered heterocycle containing 1 or 2 heteroatomsindependently selected from O and S wherein said S is in the formS(O)_(p), or phenyl optionally substituted by 1-3 R⁸.

In one set of embodiments, R³ is —C(O)OC₁-C₆alkyl, and preferablyselected from the group consisting of —C(O)O-methyl, —C(O)O-ethyl,—C(O)O-n-propyl, —C(O)O-iso-propyl, —C(O)O-iso-butyl, —C(O)O-sec-butyl,and —C(O)O-tert-butyl. It is particularly preferred in such embodimentsthat R³ is —C(O)O-tert-butyl.

Where X² is NR¹⁰ (i.e. where R³ is —C(O)NR¹⁰R¹²) it is preferred thatR¹⁰ is hydrogen or C₁-C₆alkyl (in particular methyl), or that it forms a5-7 membered (preferably 5- or 6-membered) ring system optionallycontaining from 1 to 3 additional heteroatoms independently selectedfrom S in the form of S(O)_(p), O and N, in conjunction either with R⁴and the atoms to which R¹⁰ and R⁴ are joined, or in conjunction with R¹²and the nitrogen atom to which R¹⁰ and R¹² are joined. In embodimentswhere R⁴ and R¹⁰ are joined, the skilled man will appreciate that thering system may appear as a substituted ring system bearing asubstituent on the nitrogen atom of group NR¹⁰, by virtue of substituentR¹². In these embodiments it is preferred that R¹² is hydrogen, or C₁-C₆alkyl; preferably hydrogen or C₁-C₃ alkyl; and more preferably hydrogenor methyl.

In embodiments where R¹⁰ and R¹² together with the nitrogen atom towhich they are joined form a ring system, it is preferred that said ringsystem is 5- or 6-membered. Where the ring system is 5-membered, it willpreferably contain 0 or 1 additional heteroatom independently selectedfrom O, N, or S in the form of S(O)_(p). More preferably the 1additional heteroatom will be S in the form of S(O)_(p). Where the ringsystem is 6-membered, it will preferably contain 0 or 1 additionalheteroatom independently selected from O, N, or S in the form ofS(O)_(p). More preferably the 1 additional heteroatom will be O or N,most preferably N. In one set of embodiments R¹⁰ and R¹² together withthe N-atom to which they are joined form a morpholine ring.

Where R¹⁰ does not form a ring with either R⁴ or R¹², and is hydrogen orC₁-C₆alkyl (preferably hydrogen or methyl), it is preferred that R¹² isC₁-C₄alkyl, C₁-C₃alkoxy, (CH₂)₃SCH₃, C₁-C₃haloalkyl, C₃-C₆alkynyl, or(CR^(a)R^(b))_(q)R¹¹. In such embodiments where R¹² is(CR^(a)R^(b))_(q)R¹¹, it is particularly preferred that q is 0 or 1. Itis further preferred that R¹¹ in such embodiments is an optionallysubstituted ring system selected from the group consisting ofC₃-C₆cycloalkyl, isoxazolyl, phenyl, pyridyl, pyrimidinyl,tetrahydropyranyl and morpholinyl, which, when substituted, issubstituted by 1-3 independent R⁸.

Preferably, where R⁴ does not form a ring with either R¹⁰ or R¹², R⁴ isselected from the group consisting of hydrogen, methyl, ethyl, allyl,but-2-yn-1-yl, C(O)R⁹ where R⁹ is preferably C₁-C₆alkoxy, and—(CH₂)_(q)R⁵ wherein q is 1 and R⁵ is selected from the group consistingof c-propyl, —CO₂methyl, and phenyl optionally substituted by 1-2 groupsR⁸, wherein each R⁸ is independently C₁-C₃alkyl or halogen (morepreferably in such embodiments R⁸ is methyl or fluoro). More preferablyR⁴ is selected from the group consisting of hydrogen, methyl, allyl,propoxycarbonyl, and butoxycarbonyl. More preferably still R⁴ isselected from the group consisting of hydrogen, methyl andbutoxycarbonyl.

In an alternative embodiment of the present invention, R⁴ and R¹⁰together with the atoms to which they are joined form a 5-7 memberedring system optionally containing from 1 to 3 heteroatoms independentlyselected from S, O and N, as described supra.

In yet a further alternative embodiment, R⁴ and R¹² together with theatoms to which they are joined form a 5-7 membered ring systemoptionally containing 1 or 2 additional heteroatoms independentlyselected from S, O and N. Where an additional heteroatom is S, it willbe in the form of S(O)_(p). Preferably said ring system is 6-membered.

In one embodiment R⁶ and R⁷ are both hydrogen. In another embodiment R⁶is hydrogen and R⁷ is C₁-C₆alkyl (e.g., methyl or ethyl). In anotherembodiment, R⁶ and R⁷ are both C₁-C₆alkyl. In yet a further embodimentR⁶ is hydrogen and R⁷ is —C(O)OC₄alkyl (in particular—C(O)O-tert-butyl).

Preferably R⁹ is C₁-C₆alkyl, preferably ethyl, propyl (in particulariso-propyl) or butyl (in particular tert-butyl).

Preferably R¹¹ is selected from the group consisting of C₃-C₆cycloalkyl,phenyl optionally substituted by 1-3 R⁸, a 5- or 6-memberedunsubstituted heteroaryl or 5- or 6-membered unsubstituted heterocyclylring, and a 5- or 6-membered heteroaryl or 5- or 6-membered heterocyclylring, each substituted by 1-3 R⁸. When said phenyl, heterocyclyl orheteroaryl ring is substituted, it is preferably substituted by 1 or 2R⁸.

Preferably each R⁸ is independently selected from halogen, C₁-C₃-alkylor C₁-C₃haloalkyl. More preferably each R⁸ is independently selectedfrom methyl, ethyl, chloro or fluoro, more preferably still methyl orchloro.

Table 1 below provides 33 specific examples of herbicidal compounds ofFormula (I) for use according to the invention.

TABLE 1 Specific examples of compounds of Formula (I-H) (which arecompounds of formula (I) wherein n is 0 and X¹, R², R³, and R⁴ are givenin the table) for use in the invention. (I-H)

Compound ID X¹ R² R³ R⁴ H1 N CF₃ CO₂tBu CO₂tBu H2 C—F CH₃ CO₂tBu CO₂tBuH3 N CF₃ CO₂tBu H H4 C—F CF₃ CO₂tBu H H5 C—F CF₃ CO₂tBu CO₂tBu H6 C—FOCH₃ CO₂tBu CO₂tBu H7 C—F OCH₃ CO₂tBu H H8 C—F OCH₂Ph CO₂tBu CO₂tBu H9C—F CN CO₂tBu CO₂tBu H10 C—F CN CO₂tBu H H11 C—F

CO₂tBu CO₂tBu H12 C—F

CO₂tBu CO₂tBu H13 C—F

CO₂tBu CO₂tBu H14 C—F CH═C(CH₃)₂ CO₂tBu CO₂tBu H15 C—F

CO₂tBu CO₂tBu H16 C—F Br CO₂tBu CO₂tBu H17 C—F CH₃ CO₂tBu H H18 C—FCH₂OCO₂tBu CO₂tBu CO₂tBu H19 C—F CH₃ CO₂tBu CH₃ H20 C—F CH═CH₂ CO₂tBuCO₂tBu H21 C—F CH₂CH₃ CO₂tBu CO₂tBu H22 C—F CH₂OH CO₂tBu H H23 N CH₃CO₂tBu H H24 C—F SCH₃ CO₂tBu H H25 C—SCH₃ SCH₃ CO₂tBu H H26 CF CO₂CH₃CO₂tBu CO₂tBu H27 C—F CF₂H CO₂tBu CO₂tBu H28 C—F CF₂H CO₂tBu H H29 C—F

CO₂tBu CO₂tBu H30 N CF₂H CO₂tBu H H31 N CF₂H CO₂tBu CO₂tBu H32 C—F

CO₂tBu CO₂tBu H33 C—F

CO₂tBu H

Compounds of Formula (I) may be prepared according to the followingschemes, in which the substituents of X¹, X², X³, R¹, R², R³, R⁴, R⁵,R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R^(a), R^(b), R^(c) n, p,q r and s have (unless otherwise stated explicitly) the definitionsdescribed hereinbefore, using techniques known to the person skilled inthe art of organic chemistry. General methods for the production ofcompounds of formula (I) are described below. The starting materialsused for the preparation of the compounds of the invention may bepurchased from the usual commercial suppliers or may be prepared byknown methods. The starting materials as well as the intermediates maybe purified before use in the next step by state of the artmethodologies such as chromatography, crystallization, distillation andfiltration.

Typical abbreviations used throughout are as follows:

-   app=apparent-   br.=broad-   ^(t)Bu=tert-butyl-   t-BuOH=tert-butanol-   d=doublet-   dd=double doublet-   DCM=dichloromethane-   DMF=N, N-dimethylformamide-   DMSO=dimethylsulfoxide-   DPPA=diphenylphosphoryl azide-   Et₃N=triethylamine-   Et₂O=diethyl ether-   EtOAc=ethyl acetate-   EtOH=ethanol-   HPLC=High Performance Liquid Chromatography-   m=multiplet-   Me=methyl-   MeOH=methanol-   Ph=phenyl-   q=quartet-   RT or rt=room temperature-   s=singlet-   t=triplet-   TFA=trifluoroacetic acid-   THF=tetrahydrofuran-   TMS=tetramethylsilane-   tr=retention time

Processes for preparation of compounds, e.g. a compound of formula (I)(which optionally can be an agrochemically acceptable salt thereof), arenow described, and form further aspects of the present invention. Asummary of approaches will be described first, and this will be followedby more detailed descriptions of some of the preferred approaches andtransformations.

It should be understood by those skilled in the art that the varioustransformations by which the compounds of the invention can be prepared,may be carried out in a variety of orders. For example, the bond betweenthe two heterocycles can be made by a cross-coupling reaction, afterwhich the groups NR³R⁴ and R² may be introduced or modified, or thecross-coupling reaction may be the final step in a sequence of reactionsleading to the compounds of the invention.

The pyrazines of Formula (I) can be prepared by the following eight keysteps:

(A) Linking the two heteroaromatic rings by cross-coupling. In onepreferred approach, cross-coupling is a Suzuki reaction in which a3-pyridyl- or 5-pyrimidinyl-boronic acid reacts with a halo-pyrazine,but either heterocycle can carry the required metallic (orquasi-metallic) functional group, and either can carry the complementaryhalogen or other leaving group, e.g. OSO₂CF₃.

(B) Regioselective introduction of functional groups to the pyrazinering, e.g. bromination at the 5-position of a 2-amino-pyrazine, afterwhich the new functional groups may be further modified.

(C) Formation of the group NR³R⁴ by modification of a group NH², NHR³ orNHR⁴, for example by alkoxyacylation (to form a carbamate), acylation,alkylation (either directly or by formation and then reduction of animine, i.e. reductive amination), or by Curtius rearrangement of acarboxyl group, or by Hofmann rearrangement of a primary carboxamide. Inturn, a group NH2 may be prepared, for example, by reduction of a nitroor azido group, or by hydrolysis of the product of a Curtius or Hofmannrearrangement.

(D) Introduction of the group NR³R⁴ (or a group NHR³ or NHR⁴) bydisplacement of a halogen or an alternative leaving group, e.g. OSO₂CF₃.

(E) Direct introduction of the group R², or introduction of the group R²by displacement of a leaving group at the same position on the pyrazinering, or construction of the group R² from another group at the sameposition on the pyrazine ring.

(F) N-Oxidation of the pyridine or pyrimidine ring.

(G) De novo synthesis of the pyrazine ring.

A more detailed description of some of the preferred transformations andapproaches will now be given, all shown for compounds of the inventionand intermediates in which n=0.

Compounds of Formula Ia are compounds of the invention of Formula (I) inwhich X²═O, and compounds of Formula Ib are compounds of the inventionof Formula (I) in which X²═NR10.

A compound of Formula Ia can be prepared from a compound of Formula 1using, for example, an alkoxycarbonyl alkyl carbonate of formula(R¹²O.CO)₂O, or a chloroformate of formula R¹²O.COCl, optionally in thepresence of a suitable base, and in a suitable solvent, as shown inScheme 1. If R⁴═H in the compound of Formula 1, alkoxyacylation can takeplace either once or twice, leading to a compound of the invention ofFormula Ia in which R⁴═H or in which R⁴═CO₂R¹². Reaction conditions,including ratios of reactants, can be chosen to favour one or other ofthese two products. For examples of reactions of these types, see SRégnier et al., J. Org. Chem., 2016, 81, 10348; International PatentPublication Nos. WO 2009/037247, WO 2008/153752; and K Tsuzuki and MTada, J Het. Chem., 1986, 23, 1299.

Alternatively, a compound of Formula Ia can be prepared by treatment ofan isocyanate of Formula 2 with an alcohol of formula R¹²OH, in asuitable solvent (see, for example, F Fernandez et al., Bioorg. and Med.Chem., 2009, 17, 3618). Isocyanates of Formula 2 can be prepared bytreatment of the corresponding amino-pyrazines with phosgene or anequivalent reagent such as triphosgene (see, for example, J S Nowick etal., J. Org. Chem., 1992, 57, 7364 and P Majer and R S Randad, J. Org.Chem., 1994, 59, 1937). Alternatively, isocyanates of Formula 2 can beprepared from the corresponding pyrazine-2-carboxylic acids by a Curtiusrearrangement or one of the related rearrangements, as described inscheme 2 below.

A compound of Formula Ia in which R⁴ is not hydrogen can be preparedfrom a compound of Formula Ia in which R⁴═H, as shown in Scheme 3. IfR⁴═CO₂R¹² in the product of this reaction, the conversion can be carriedout in the same way as described above (Scheme 1), and similar reactionswill lead to compounds of Formula Ia in which R⁴=acyl. If R⁴=alkyl,alkoxyalkyl, haloalkyl, haloalkoxyalkyl, cycloalkyl, allyl or propargylin the product, the reaction can be carried out using a suitable reagentof formula R⁴-LG, in which LG is a leaving group such as a halogen orOSO₂CH₃, optionally in the presence of a base, and in a suitable solvent(see, for example, M Chioua et al., Eur. J. Org. Chem., 2013, 35).Compounds of formula R⁴-LG are commercially available or can be preparedby methods described in the literature.

A compound of Formula Ib in which R¹⁰ and R¹² are not hydrogen can beprepared from a compound of Formula 1 by treatment with a carbamoylchloride of formula R¹⁰R¹²N.CO.Cl, in a suitable solvent, and usually inthe presence of a base, as shown in Scheme 4 (see, for example,Boehringer Ingelheim International GMBH, WO 2008/113760). Carbamoylchlorides of formula R¹⁰R¹²N.CO.Cl are commercially available or can beprepared by methods described in the literature.

A compound of Formula Ib in which R¹⁰═H can be prepared by treatment ofa compound of Formula 1 with an isocyanate of formula R¹²NCO, in asuitable solvent and optionally in the presence of a base, as shown inScheme 4 (see, for example, G Heinisch et al., J. Het. Chem., 1995, 32,13). Isocyanates of formula R¹²NCO can be prepared, for example, fromthe corresponding primary amines of formula R¹²NH2, or by Curtiusrearrangement of carboxylic acids of formula R¹²CO2H, using methodsdescribed in the literature.

A compound of Formula Ib can be made from a compound of Formula 3 inwhich U is a leaving group such as imidazol-1-yl or aryloxy by treatmentwith an amine of formula R¹⁰R¹²NH, in a suitable solvent, and optionallyin the presence of a suitable base, as shown in Scheme 5.

In turn, a compound of Formula 3 can be made from a compound of Formula1 by treatment, for example, with 1,1′-carbonyldiimidazole(U=imidazol-1-yl) or an aryl chloroformate (U=aryloxy), in a suitablesolvent in each case and, for the aryl chloroformate, usually in thepresence of a base, as shown above in Scheme 5.

For examples of reactions of this kind using 1,1′-carbonyldiimidazole,see International Patent Publication No. WO 2005/066145. For examples ofreactions of this kind using phenyl chloroformate, see InternationalPatent Publication No. WO 2008/153752.

A compound of Formula Ib in which R⁴═H can be made from an isocyanate ofFormula 2 by treatment with an amine of formula R¹⁰R¹²NH, in a suitablesolvent. See, for example, R Aslanian et al., Bioorg. Med. Chem. Letts.,2002, 12, 937.

A compound of Formula Ib in which R⁴ is not hydrogen can be preparedfrom a compound of Formula Ib in which R⁴═H, as shown in Scheme 7. IfR⁴═CO₂R¹² in the product, the conversion can be carried out in the sameway as described above (Scheme 1), and similar reactions will lead tocompounds of Formula Ia in which R⁴=acyl. If R⁴=alkyl, alkoxyalkyl,haloalkyl, haloalkoxyalkyl, cycloalkyl, allyl or propargyl in theproduct, the reaction can be carried out using a suitable reagent offormula R⁴-LG, in which LG is a leaving group such as a halogen orOSO₂CH3, optionally in the presence of a base, and in a suitable solvent(see, for example, Abbott GMBH & CO. K.G., WO 2008/046919). Compounds offormula R⁴-LG are commercially available or can be prepared by methodsdescribed in the literature.

A compound of Formula 1 in which R⁴ is alkyl, alkoxyalkyl, haloalkyl,haloalkoxyalkyl, cycloalkyl, allyl or propargyl can be prepared from acompound of Formula 4 by treatment with a reagent R⁴-LG, in which LG isa leaving group such as a halogen or OSO₂CH3, optionally in the presenceof a base, and in a suitable solvent, as shown in Scheme 8 (see, forexample, P Jeanjot et al., Synthesis, 2003, 513). Compounds of formulaR⁴-LG are commercially available or can be prepared by methods describedin the literature.

Amino-pyrazines can also be mono-methylated on the amino-group usingmethanol, sodium hydroxide and an iridium catalyst (see F Li et al., RSCAdvances, 2012, 2, 8645). Related N-alkylations using other alcoholshave also been reported (see, for example, S Li et al., Green Chem.,2015, 17, 3260).

In an alternative approach, a compound of Formula 1 in which R⁴ is nothydrogen can be prepared from a compound of Formula 4 by reaction withan aldehyde R^(W)—CHO, in which R^(W)—CH₂═R⁴, in the presence of areducing agent, and in a suitable solvent, as shown in Scheme 9 (forexamples, see P Jeanjot et al., Synthesis, 2003, 513). Ketones can alsobe used instead of the aldehyde R^(W)—CHO, and lead to branchedsubstituents on the amino group (see, for example, International PatentPublication No. WO 2011/073149). Aldehydes of formula R^(W)—CHO and thecorresponding ketones are commercially available or can be prepared bymethods described in the literature.

Amino-pyrazines can also be mono-alkylated (or mono-benzylated, etc.) byacylation at the amino-group and then reduction of the resulting amideusing, for example, lithium aluminium hydride, in a suitable solvent(for examples, see P Jeanjot et al., Synthesis, 2003, 513).

In an alternative approach, a compound of Formula 1 may be prepared froma compound of Formula 5, in which W is a suitable halogen, such as Cl,Br or I, or another suitable leaving group, such as OSO₂CF₃, by reactionwith an amine of formula R⁴NH₂, optionally in the presence of a suitablecatalyst and/or a suitable ligand and/or a suitable base, and in asuitable solvent, as shown in Scheme 10. For examples of reactions ofthis kind, see A J Henderson et al., Bioorg. and Med. Chem. Letts.,2010, 20, 1137, and P J J Colbon et al., J Het. Chem., 2008, 45, 1451.Amines of formula R⁴NH2 are commercially available or can be prepared bymethods described in the literature.

A compound of the invention of Formula Ia may also be prepared byreaction of a pyrazine of Formula 5, in which W is a suitable halogen,such as Cl, Br or I, or another suitable leaving group, such as OSO₂CF₃,with a carbamate of formula R¹²O.C(O).NHR⁴, optionally in the presenceof a suitable catalyst and/or a suitable ligand and/or a suitable base,and in a suitable solvent, as shown in Scheme 11.

For examples of reactions of this kind, with and without palladiumcatalysis, see International Patent Publication No. WO 03/000666 and DFalcone et al., Tet. Letts., 2014, 55, 2646. Carbamates of formulaR¹²O.C(O).NHR⁴ are commercially available or may be prepared by methodsdescribed in the literature.

In a similar way, a compound of the invention of Formula Ib may beprepared by reaction of a pyrazine of Formula 5 with a urea of formulaR¹⁰R¹²N.C(O).NHR⁴, optionally in the presence of a suitable catalystand/or a suitable ligand and/or a suitable base, and in a suitablesolvent, as shown above in Scheme 11. For examples of related reactions,see J B Ernst et al., Org. Letts., 2014, 16, 3844. Ureas of formulaR¹⁰R¹²N.C(O).NHR⁴ are commercially available or may be prepared bymethods described in the literature.

A compound of Formula 4 can be prepared by reduction of thecorresponding nitro-compound, optionally in the presence of a catalyst,and in a suitable solvent, as shown in Scheme 12 (see, for example,International Patent Publication No. WO 2013/078254).

Similarly, a compound of Formula 4 can be prepared by reduction of thecorresponding azide, optionally in the presence of a catalyst and in asuitable solvent (see, for example, N Sato et al., Synthesis, 1994,931).

In an alternative approach, a compound of the invention of Formula Ia inwhich R⁴═H can be prepared by a Curtius rearrangement of thecorresponding carboxylic acid, in a suitable solvent, as shown in Scheme13.

The first-formed product of the rearrangement is an isocyanate, buttreatment with an alcohol of formula R¹²OH, usually in the same reactionvessel, leads to a compound of the invention of Formula Ia in whichR⁴═H. Alternatively, the intermediate isocyanate can be hydrolysed togive the amino-pyrazine of Formula 4. For examples of Curtius reactionsof this kind, see S Sunami and M Ohkubo, Tetrahedron, 2009, 65, 638. Thestarting carboxylic acids shown in Scheme 13 can be prepared, forexample, by hydrolysis of the corresponding methyl or ethyl esters.

Compounds of the invention of Formula Ib in which R⁴═H can also beprepared by a Curtius rearrangement, the first-formed isocyanate beingtreated with an amine of formula R¹⁰R¹²NH. For examples of Curtiusreactions of this kind, see Millenium Pharmaceuticals, Inc., WO03/101444.

The same transformations can also be carried out using the Schmidtreaction or the Lossen rearrangement.

In a related approach, a compound of the invention of Formula Ia inwhich R⁴═H can be prepared by a Hofmann rearrangement of thecorresponding primary carboxamide, in a suitable solvent, as shown inScheme 14 (see, for example, G Madhusudhan et al., Org. Chem.: An IndianJournal, 2009, 5, 274).

The first-formed product of the rearrangement is an isocyanate, buttreatment with an alcohol of formula R¹²OH, usually in the same reactionvessel, leads to a compound of the invention of Formula Ia in whichR⁴═H. Alternatively, the intermediate isocyanate can be hydrolysed togive the amino-pyrazine of Formula 4. The starting carboxamide shown inScheme 7 can be prepared, for example, from the corresponding carboxylicacid via the acid chloride, or from the corresponding methyl or ethylester, or by partial hydrolysis of the corresponding cyanide.

Compounds of the invention of Formula Ib in which R⁴═H can also beprepared by a Hofmann rearrangement, the first-formed isocyanate beingtreated with an amine of formula R¹⁰R¹²NH. For examples of reactions ofthis kind, see P Liu et al., Eur. J. Org. Chem., 2012, 1994.

A compound of the invention of Formula (I) can also be prepared by across-coupling reaction, as shown in Scheme 15. The cross-couplingpartners can be a pyrazine of Formula 6, in which Y is chlorine,bromine, iodine or a pseudohalogen such as OSO₂CF₃, and a pyridine orpyrimidine of Formula 7, in which Q is the group B(OR^(Y))₂ (this ispreferred) or Sn(R^(Z))₃ (in which R^(Y)═H or alkyl or the two groupsR^(Y) may join to form a ring, and R^(Z)=alkyl), in the presence of asuitable catalyst, usually a palladium catalyst, and optionally in thepresence of a suitable ligand and/or a suitable base, and in a suitablesolvent. Alternatively, the cross-coupling partners can be a pyrazine ofFormula 6, in which Y is the group B(OR^(Y))₂ (this is preferred) orSn(R^(Z))₃, and a pyridine or pyrimidine of Formula 7, in which Q ischlorine, bromine, iodine or a pseudohalogen such as OSO₂CF₃, in thepresence of a suitable catalyst, usually a palladium catalyst, andoptionally in the presence of a suitable ligand and/or a suitable base,and in a suitable solvent.

For examples of cross-coupling reactions of the type shown in Scheme 15,see US Patent Application Publication No. 2010/0099684, J J Caldwell etal., Tetrahedron, 2012, 68, 9713, and K Chen et al., Tet. Letts., 2012,53, 4873.

A pyrazine of Formula 6 can be prepared by functionalisation of apyrazine of Formula 8, as shown in Scheme 16. For example, whenY=bromine, this can be carried out by bromination using bromine orN-bromosuccinimide, or when Y=iodine, this can be carried out byiodination using iodine or N-iodosuccinimide, or when Y=B(OR^(Y))₂ thiscan be carried out by reaction of the corresponding pyrazine in whichY=bromine or iodine with (R^(Y)O)₂B—B(OR^(Y))₂ under palladiumcatalysis, in a suitable solvent in each case. For an example of abromination of this kind, see International Patent Publication No. WO2010/071837.

Pyridines and pyrimidines of Formula 7 are commercially available or canbe made by methods described in the literature.

It will be understood by those skilled in the art that cross-couplingreactions of the types shown in Scheme 15 can also be carried out in asimilar way on related pyrazines which, instead of NR³R⁴ and/or R²,contain groups which are then converted into NR³R⁴ and/or R² after thecross-coupling reaction, using methods such as those shown in Schemes 1,4, 5, 11, 13 and 14. The group NR³R⁴ may also be modified aftercross-coupling, using methods such as those shown in Schemes 3 and 7.

In an alternative approach, a compound of Formula (I) can be preparedfrom a compound of Formula 9 by the method shown in Scheme 17.

In the first step, a group Z, which may be a halogen, alkylthio ornitro, is introduced directly to give a compound of Formula 10. Forexample, if Z=bromine, it can be introduced using bromine orN-bromosuccinimide, in a suitable solvent (see for example N Sato and RTakeuchi, Synthesis, 1990, 659). If Z is equal to a claimed value of R²,this constitutes a way of directly introducing the group R² to preparethe corresponding compounds of the invention of Formula (I).Alternatively, the group Z can be converted in one or more steps bymethods reported in the literature into the group R² to give a compoundof the invention of Formula (I). For example, if the group Z is bromine,a substituent R² which is alkyl, cycloalkyl, alkenyl or aryl may beintroduced by palladium-catalysed cross-coupling, and a substituent R²which is alkynyl may be introduced using a Sonogashira reaction, in asuitable solvent in each case.

Pyrazines of Formula 11, in which M is chlorine, bromine, iodine or apseudohalogen such as OSO₂CF₃, and related compounds in which the groupNR³R⁴ is replaced, for example, by NH₂ or NH-alkyl, can reactregioselectively at the 3-position in displacement and cross-couplingreactions, as exemplified in Scheme 18. For example, the 3-bromo-groupof 2-amino-3,5-dibromo-pyrazine is selectively displaced with alkoxidesor secondary amines (see Examples 3-O and 3-P of International PatentPublication No. WO 2003/000666).

A compound of the invention of Formula (I) can also be prepared byapproaches which involve the de novo synthesis of the pyrazine ring. Avariety of such approaches have been reported in the literature. See,for example, Section 6.03.10 of Chapter 6.03, Pyrazines and their BenzoDerivatives, by N Sato, in Vol. 6 of Comprehensive HeterocyclicChemistry II, Editors A R Katritzky, C W Rees and F V Scriven, Pergamon,1996; N Sato, Science of Synthesis, 2004, 16, 751; and M P Cabal, ModernHeterocyclic Chemistry, 2011, 3, 1683. Representative examples ofpyrazine ring syntheses are shown in Schemes 19 and 20 below.

Scheme 19 shows the reaction of a 1,2-diamine with an acyl cyanide whichleads, following oxidation, to 2-amino-3-substituted-pyrazines (see, forexample, R Lakhan and B J Rai, Synthesis, 1987, 914).

Scheme 20 shows a two-step approach to3-substituted-5-aryl/heteroaryl-pyrazin-2-ones (see, for example, R HBradbury et al., Heterocycles, 1990, 31, 1647). These pyrazin-2-ones canbe converted, using methods reported in the literature, into thecorresponding pyrazines with a group W at the 2-position, where W is ahalogen, such as Cl, Br or I, or a group such as OSO₂CF₃. In turn, thesepyrazines can be converted into compounds of the invention of Formula(I), as shown in Scheme 11.

The compounds of Formula (I) as described herein may be used asherbicides by themselves, but they are generally formulated intoherbicidal compositions using formulation adjuvants, such as carriers,solvents and surface-active agents (SFAs). Thus, the present inventionfurther provides a herbicidal composition comprising a herbicidalcompound as described herein and an agriculturally acceptableformulation adjuvant. The composition can be in the form of concentrateswhich are diluted prior to use, although ready-to-use compositions canalso be made. The final dilution is usually made with water, but can bemade instead of, or in addition to, water, with, for example, liquidfertilisers, micronutrients, biological organisms, oil or solvents.

Such herbicidal compositions generally comprise from 0.1 to 99% byweight, especially from 0.1 to 95% by weight of compounds of Formula (I)and from 1 to 99.9% by weight of a formulation adjuvant, whichpreferably includes from 0 to 25% by weight of a surface-activesubstance.

The compositions can be chosen from a number of formulation types, manyof which are known from the Manual on Development and Use of FAOSpecifications for Plant Protection Products, 5th Edition, 1999. Theseinclude dustable powders (DP), soluble powders (SP), water solublegranules (SG), water dispersible granules (WG), wettable powders (WP),granules (GR) (slow or fast release), soluble concentrates (SL), oilmiscible liquids (OL), ultra low volume liquids (UL), emulsifiableconcentrates (EC), dispersible concentrates (DC), emulsions (both oil inwater (EW) and water in oil (EO), micro-emulsions (ME), suspensionconcentrates (SC), aerosols, capsule suspensions (CS) and seed treatmentformulations. The formulation type chosen in any instance will dependupon the particular purpose envisaged and the physical, chemical andbiological properties of the compound of Formula (I).

Dustable powders (DP) may be prepared by mixing a compound of Formula(I) with one or more solid diluents (for example natural clays, kaolin,pyrophyllite, bentonite, alumina, montmorillonite, kieselguhr, chalk,diatomaceous earths, calcium phosphates, calcium and magnesiumcarbonates, sulphur, lime, flours, talc and other organic and inorganicsolid carriers) and mechanically grinding the mixture to a fine powder.

Soluble powders (SP) may be prepared by mixing a compound of Formula (I)with one or more water-soluble inorganic salts (such as sodiumbicarbonate, sodium carbonate or magnesium sulphate) or one or morewater-soluble organic solids (such as a polysaccharide) and, optionally,one or more wetting agents, one or more dispersing agents or a mixtureof said agents to improve water dispersibility/solubility. The mixtureis then ground to a fine powder. Similar compositions may also begranulated to form water soluble granules (SG).

Wettable powders (WP) may be prepared by mixing a compound of Formula(I) with one or more solid diluents or carriers, one or more wettingagents and, preferably, one or more dispersing agents and, optionally,one or more suspending agents to facilitate the dispersion in liquids.The mixture is then ground to a fine powder. Similar compositions mayalso be granulated to form water dispersible granules (WG).

Granules (GR) may be formed either by granulating a mixture of acompound of Formula (I) and one or more powdered solid diluents orcarriers, or from pre-formed blank granules by absorbing a compound ofFormula (I) (or a solution thereof, in a suitable agent) in a porousgranular material (such as pumice, attapulgite clays, fuller's earth,kieselguhr, diatomaceous earths or ground corn cobs) or by adsorbing acompound of Formula (I) (or a solution thereof, in a suitable agent) onto a hard core material (such as sands, silicates, mineral carbonates,sulphates or phosphates) and drying if necessary. Agents which arecommonly used to aid absorption or adsorption include solvents (such asaliphatic and aromatic petroleum solvents, alcohols, ethers, ketones andesters) and sticking agents (such as polyvinyl acetates, polyvinylalcohols, dextrins, sugars and vegetable oils). One or more otheradditives may also be included in granules (for example an emulsifyingagent, wetting agent or dispersing agent).

Dispersible Concentrates (DC) may be prepared by dissolving a compoundof Formula (I) in water or an organic solvent, such as a ketone, alcoholor glycol ether. These solutions may contain a surface active agent (forexample to improve water dilution or prevent crystallisation in a spraytank).

Emulsifiable concentrates (EC) or oil-in-water emulsions (EW) may beprepared by dissolving a compound of Formula (I) in an organic solvent(optionally containing one or more wetting agents, one or moreemulsifying agents or a mixture of said agents). Suitable organicsolvents for use in ECs include aromatic hydrocarbons (such asalkylbenzenes or alkylnaphthalenes, exemplified by SOLVESSO 100,SOLVESSO 150 and SOLVESSO 200; SOLVESSO is a Registered Trade Mark),ketones (such as cyclohexanone or methylcyclohexanone) and alcohols(such as benzyl alcohol, furfuryl alcohol or butanol),N-alkylpyrrolidones (such as N-methylpyrrolidone or N-octylpyrrolidone),dimethyl amides of fatty acids (such as C₈-C₁₀ fatty acid dimethylamide)and chlorinated hydrocarbons. An EC product may spontaneously emulsifyon addition to water, to produce an emulsion with sufficient stabilityto allow spray application through appropriate equipment.

Preparation of an EW involves obtaining a compound of Formula (I) eitheras a liquid (if it is not a liquid at room temperature, it may be meltedat a reasonable temperature, typically below 70° C.) or in solution (bydissolving it in an appropriate solvent) and then emulsifying theresultant liquid or solution into water containing one or more SFAs,under high shear, to produce an emulsion. Suitable solvents for use inEWs include vegetable oils, chlorinated hydrocarbons (such aschlorobenzenes), aromatic solvents (such as alkylbenzenes oralkylnaphthalenes) and other appropriate organic solvents which have alow solubility in water.

Microemulsions (ME) may be prepared by mixing water with a blend of oneor more solvents with one or more SFAs, to produce spontaneously athermodynamically stable isotropic liquid formulation. A compound ofFormula (I) is present initially in either the water or the solvent/SFAblend. Suitable solvents for use in MEs include those hereinbeforedescribed for use in in ECs or in EWs. An ME may be either anoil-in-water or a water-in-oil system (which system is present may bedetermined by conductivity measurements) and may be suitable for mixingwater-soluble and oil-soluble pesticides in the same formulation. An MEis suitable for dilution into water, either remaining as a microemulsionor forming a conventional oil-in-water emulsion.

Suspension concentrates (SC) may comprise aqueous or non-aqueoussuspensions of finely divided insoluble solid particles of a compound ofFormula (I). SCs may be prepared by ball or bead milling the solidcompound of Formula (I) in a suitable medium, optionally with one ormore dispersing agents, to produce a fine particle suspension of thecompound. One or more wetting agents may be included in the compositionand a suspending agent may be included to reduce the rate at which theparticles settle. Alternatively, a compound of Formula (I) may be drymilled and added to water, containing agents hereinbefore described, toproduce the desired end product.

Aerosol formulations comprise a compound of Formula (I) and a suitablepropellant (for example n-butane). A compound of Formula (I) may also bedissolved or dispersed in a suitable medium (for example water or awater miscible liquid, such as n-propanol) to provide compositions foruse in non-pressurised, hand-actuated spray pumps.

Capsule suspensions (CS) may be prepared in a manner similar to thepreparation of EW formulations but with an additional polymerisationstage such that an aqueous dispersion of oil droplets is obtained, inwhich each oil droplet is encapsulated by a polymeric shell and containsa compound of Formula (I) and, optionally, a carrier or diluenttherefor. The polymeric shell may be produced by either an interfacialpolycondensation reaction or by a coacervation procedure. Thecompositions may provide for controlled release of the compound ofFormula (I) and they may be used for seed treatment. A compound ofFormula (I) may also be formulated in a biodegradable polymeric matrixto provide a slow, controlled release of the compound.

The composition may include one or more additives to improve thebiological performance of the composition, for example by improvingwetting, retention or distribution on surfaces; resistance to rain ontreated surfaces; or uptake or mobility of a compound of Formula (I).Such additives include surface active agents (SFAs), spray additivesbased on oils, for example certain mineral oils or natural plant oils(such as soy bean and rape seed oil), and blends of these with otherbio-enhancing adjuvants (ingredients which may aid or modify the actionof a compound of Formula (I)).

Wetting agents, dispersing agents and emulsifying agents may be SFAs ofthe cationic, anionic, amphoteric or non-ionic type.

Suitable SFAs of the cationic type include quaternary ammonium compounds(for example cetyltrimethyl ammonium bromide), imidazolines and aminesalts.

Suitable anionic SFAs include alkali metals salts of fatty acids, saltsof aliphatic monoesters of sulphuric acid (for example sodium laurylsulphate), salts of sulphonated aromatic compounds (for example sodiumdodecylbenzenesulphonate, calcium dodecylbenzenesulphonate,butylnaphthalene sulphonate and mixtures of sodium di-isopropyl- andtri-isopropyl-naphthalene sulphonates), ether sulphates, alcohol ethersulphates (for example sodium laureth-3-sulphate), ether carboxylates(for example sodium laureth-3-carboxylate), phosphate esters (productsfrom the reaction between one or more fatty alcohols and phosphoric acid(predominately mono-esters) or phosphorus pentoxide (predominatelydi-esters), for example the reaction between lauryl alcohol andtetraphosphoric acid; additionally these products may be ethoxylated),sulphosuccinamates, paraffin or olefine sulphonates, taurates andlignosulphonates.

Suitable SFAs of the amphoteric type include betaines, propionates andglycinates.

Suitable SFAs of the non-ionic type include condensation products ofalkylene oxides, such as ethylene oxide, propylene oxide, butylene oxideor mixtures thereof, with fatty alcohols (such as oleyl alcohol or cetylalcohol) or with alkylphenols (such as octylphenol, nonylphenol oroctylcresol); partial esters derived from long chain fatty acids orhexitol anhydrides; condensation products of said partial esters withethylene oxide; block polymers (comprising ethylene oxide and propyleneoxide); alkanolamides; simple esters (for example fatty acidpolyethylene glycol esters); amine oxides (for example lauryl dimethylamine oxide); and lecithins.

Suitable suspending agents include hydrophilic colloids (such aspolysaccharides, polyvinylpyrrolidone or sodium carboxymethylcellulose)and swelling clays (such as bentonite or attapulgite).

Herbicidal compositions as described herein may further comprise atleast one additional pesticide. For example, the compounds of formula(I) can also be used in combination with other herbicides or plantgrowth regulators. In a preferred embodiment the additional pesticide isa herbicide and/or herbicide safener. Examples of such mixtures are, inwhich ‘I’ represents a compound of Formula (I), I+acetochlor,I+acifluorfen, I+acifluorfen-sodium, I+aclonifen, I+acrolein,I+alachlor, I+alloxydim, I+ametryn, I+amicarbazone, I+amidosulfuron,I+aminopyralid, I+amitrole, I+anilofos, I+asulam, I+atrazine,I+azafenidin, I+azimsulfuron, I+BCPC, I+beflubutamid, I+benazolin,I+bencarbazone, I+benfluralin, I+benfuresate, I+bensulfuron,I+bensulfuron-methyl, I+bensulide, I+bentazone, I+benzfendizone,I+benzobicyclon, I+benzofenap, I+bicyclopyrone, I+bifenox, I+bilanafos,I+bispyribac, I+bispyribac-sodium, I+borax, I+bromacil, I+bromobutide,I+bromoxynil, I+butachlor, I+butamifos, I+butralin, I+butroxydim,I+butylate, I+cacodylic acid, I+calcium chlorate, I+cafenstrole,I+carbetamide, I+carfentrazone, I+carfentrazone-ethyl, I+chlorflurenol,I+chlorflurenol-methyl, I+chloridazon, I+chlorimuron,I+chlorimuron-ethyl, I+chloroacetic acid, I+chlorotoluron,I+chlorpropham, I+chlorsulfuron, I+chlorthal, I+chlorthal-dimethyl,I+cinidon-ethyl, I+cinmethylin, I+cinosulfuron, I+cisanilide,I+clethodim, I+clodinafop, I+clodinafop-propargyl, I+clomazone,I+clomeprop, I+clopyralid, I+cloransulam, I+cloransulam-methyl,I+cyanazine, I+cycloate, I+cyclosulfamuron, I+cycloxydim, I+cyhalofop,I+cyhalofop-butyl, I+2,4-D, I+daimuron, I+dalapon, I+dazomet, I+2,4-DB,I+I+desmedipham, I+dicamba, I+dichlobenil, I+dichlorprop,I+dichlorprop-P, I+diclofop, I+diclofop-methyl, I+diclosulam,I+difenzoquat, I+difenzoquat metilsulfate, I+diflufenican,I+diflufenzopyr, I+dimefuron, I+dimepiperate, I+dimethachlor,I+dimethametryn, I+dimethenamid, I+dimethenamid-P, I+dimethipin,I+dimethylarsinic acid, I+dinitramine, I+dinoterb, I+diphenamid,I+dipropetryn, I+diquat, I+diquat dibromide, I+dithiopyr, I+diuron,I+endothal, I+EPTC, I+esprocarb, I+ethalfluralin, I+ethametsulfuron,I+ethametsulfuron-methyl, I+ethephon, I+ethofumesate, I+ethoxyfen,I+ethoxysulfuron, I+etobenzanid, I+fenoxaprop-P, I+fenoxaprop-P-ethyl,I+fentrazamide, I+ferrous sulfate, I+flamprop-M, I+flazasulfuron,I+florasulam, I+fluazifop, I+fluazifop-butyl, I+fluazifop-P,I+fluazifop-P-butyl, I+fluazolate, I+flucarbazone,I+flucarbazone-sodium, I+flucetosulfuron, I+fluchloralin, I+flufenacet,I+flufenpyr, I+flufenpyr-ethyl, I+flumetralin, I+flumetsulam,I+flumiclorac, I+flumiclorac-pentyl, I+flumioxazin, I+flumipropin,I+fluometuron, I+fluoroglycofen, I+fluoroglycofen-ethyl, I+fluoxaprop,I+flupoxam, I+flupropacil, I+flupropanate, I+flupyrsulfuron,I+flupyrsulfuron-methyl-sodium, I+flurenol, I+fluridone,I+flurochloridone, I+fluroxypyr, I+flurtamone, I+fluthiacet,I+fluthiacet-methyl, I+fomesafen, I+foramsulfuron, I+fosamine,I+glufosinate, I+glufosinate-ammonium, I+glyphosate, I+halauxifen,I+halosulfuron, I+halosulfuron-methyl, I+haloxyfop, I+haloxyfop-P,I+hexazinone, I+imazamethabenz, I+imazamethabenz-methyl, I+imazamox,I+imazapic, I+imazapyr, I+imazaquin, I+imazethapyr, I+imazosulfuron,I+indanofan, I+indaziflam, I+iodomethane, I+iodosulfuron,I+iodosulfuron-methyl-sodium, I+ioxynil, I+isoproturon, I+isouron,I+isoxaben, I+isoxachlortole, I+isoxaflutole, I+isoxapyrifop,I+karbutilate, I+lactofen, I+lenacil, I+linuron, I+mecoprop,I+mecoprop-P, I+mefenacet, I+mefluidide, I+mesosulfuron,I+mesosulfuron-methyl, I+mesotrione, I+metam, I+metamifop, I+metamitron,I+metazachlor, I+methabenzthiazuron, I+methazole, I+methylarsonic acid,I+methyldymron, I+methyl isothiocyanate, I+metolachlor, I+S-metolachlor,I+metosulam, I+metoxuron, I+metribuzin, I+metsulfuron,I+metsulfuron-methyl, I+molinate, I+monolinuron, I+naproanilide,I+napropamide, I+naptalam, I+neburon, I+nicosulfuron, I+n-methylglyphosate, I+nonanoic acid, I+norflurazon, I+oleic acid (fatty acids),I+orbencarb, I+orthosulfamuron, I+oryzalin, I+oxadiargyl, I+oxadiazon,I+oxasulfuron, I+oxaziclomefone, I+oxyfluorfen, I+paraquat, I+paraquatdichloride, I+pebulate, I+pendimethalin, I+penoxsulam,I+pentachlorophenol, I+pentanochlor, I+pentoxazone, I+pethoxamid,I+phenmedipham, I+picloram, I+picolinafen, I+pinoxaden, I+piperophos,I+pretilachlor, I+primisulfuron, I+primisulfuron-methyl, I+prodiamine,I+profoxydim, I+prohexadione-calcium, I+prometon, I+prometryn,I+propachlor, I+propanil, I+propaquizafop, I+propazine, I+propham,I+propisochlor, I+propoxycarbazone, I+propoxycarbazone-sodium,I+propyzamide, I+prosulfocarb, I+prosulfuron, I+pyraclonil,I+pyraflufen, I+pyraflufen-ethyl, I+pyrasulfotole, I+pyrazolynate,I+pyrazosulfuron, I+pyrazosulfuron-ethyl, I+pyrazoxyfen, I+pyribenzoxim,I+pyributicarb, I+pyridafol, I+pyridate, I+pyriftalid, I+pyriminobac,I+pyriminobac-methyl, I+pyrimisulfan, I+pyrithiobac,I+pyrithiobac-sodium, I+pyroxasulfone, I+pyroxsulam, I+quinclorac,I+quinmerac, I+quinoclamine, I+quizalofop, I+quizalofop-P,I+rimsulfuron, I+saflufenacil, I+sethoxydim, I+siduron, I+simazine,I+simetryn, I+sodium chlorate, I+sulcotrione, I+sulfentrazone,I+sulfometuron, I+sulfometuron-methyl, I+sulfosate, I+sulfosulfuron,I+sulfuric acid, I+tebuthiuron, I+tefuryltrione, I+tembotrione,I+tepraloxydim, I+terbacil, I+terbumeton, I+terbuthylazine, I+terbutryn,I+thenylchlor, I+thiazopyr, I+thifensulfuron, I+thiencarbazone,I+thifensulfuron-methyl, I+thiobencarb, I+topramezone, I+tralkoxydim,I+tri-allate, I+triasulfuron, I+triaziflam, I+tribenuron,I+tribenuron-methyl, I+triclopyr, I+trietazine, I+trifloxysulfuron,I+trifloxysulfuron-sodium, I+trifluralin, I+triflusulfuron,I+triflusulfuron-methyl, I+trihydroxytriazine, I+trinexapac-ethyl,I+tritosulfuron,I+[3-[2-chloro-4-fluoro-5-(1-methyl-6-trifluoromethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-3-yl)phenoxy]-2-pyridyloxy]aceticacid ethyl ester (CAS RN 353292-31-6). The compounds of formula (I)and/or compositions of the present invention may also be combined withherbicidal compounds disclosed in WO06/024820 and/or WO07/096576.

The mixing partners of the compound of Formula (I) may also be in theform of esters or salts, as mentioned e.g. in The Pesticide Manual,Sixteenth Edition, British Crop Protection Council, 2012.

The compound of Formula (I) can also be used in mixtures with otheragrochemicals such as fungicides, nematicides or insecticides, examplesof which are given in The Pesticide Manual (supra).

The mixing ratio of the compound of Formula (I) to the mixing partner ispreferably from 1:100 to 1000:1.

The mixtures can advantageously be used in the above-mentionedformulations (in which case “active ingredient” relates to therespective mixture of compound of Formula I with the mixing partner).

The compounds of Formula (I) as described herein can also be used incombination with one or more safeners. Likewise, mixtures of a compoundof Formula (I) as described herein with one or more further herbicidescan also be used in combination with one or more safeners. The safenerscan be AD 67 (MON 4660), benoxacor, cloquintocet-mexyl, cyprosulfamide(CAS RN 221667-31-8), dichlormid, fenchlorazole-ethyl, fenclorim,fluxofenim, furilazole and the corresponding R isomer, isoxadifen-ethyl,mefenpyr-diethyl, oxabetrinil,N-isopropyl-4-(2-methoxy-benzoylsulfamoyl)-benzamide (CAS RN221668-34-4). Other possibilities include safener compounds disclosedin, for example, EP0365484 e.gN-(2-methoxybenzoyl)-4-[(methylaminocarbonyl)amino]benzenesulfonamide.Particularly preferred are mixtures of a compound of Formula I withcyprosulfamide, isoxadifen-ethyl, cloquintocet-mexyl and/orN-(2-methoxybenzoyI)-4-[(methyl-aminocarbonyl)amino]benzenesulfonamide.

The safeners of the compound of Formula (I) may also be in the form ofesters or salts, as mentioned e.g. in The Pesticide Manual (supra). Thereference to cloquintocet-mexyl also applies to a lithium, sodium,potassium, calcium, magnesium, aluminium, iron, ammonium, quaternaryammonium, sulfonium or phosphonium salt thereof as disclosed in WO02/34048, and the reference to fenchlorazole-ethyl also applies tofenchlorazole, etc.

Preferably the mixing ratio of compound of Formula (I) to safener isfrom 100:1 to 1:10, especially from 20:1 to 1:1.

The mixtures can advantageously be used in the above-mentionedformulations (in which case “active ingredient” relates to therespective mixture of compound of Formula (I) with the safener).

As described above, compounds of formula (I) and/or compositionscomprising such compounds may be used in methods of controlling unwantedplant growth, and in particular in controlling unwanted plant growth incrops of useful plants. Thus, the present invention further provides amethod of selectively controlling weeds at a locus comprising cropplants and weeds, wherein the method comprises application to the locus,of a weed-controlling amount of a compound of formula (I), or acomposition as described herein. ‘Controlling’ means killing, reducingor retarding growth or preventing or reducing germination. Generally theplants to be controlled are unwanted plants (weeds). ‘Locus’ means thearea in which the plants are growing or will grow.

The rates of application of compounds of Formula (I) may vary withinwide limits and depend on the nature of the soil, the method ofapplication (pre- or post-emergence; seed dressing; application to theseed furrow; no tillage application etc.), the crop plant, the weed(s)to be controlled, the prevailing climatic conditions, and other factorsgoverned by the method of application, the time of application and thetarget crop. The compounds of Formula I according to the invention aregenerally applied at a rate of from 10 to 2000 g/ha, especially from 50to 1000 g/ha.

The application is generally made by spraying the composition, typicallyby tractor mounted sprayer for large areas, but other methods such asdusting (for powders), drip or drench can also be used.

Useful plants in which the composition according to the invention can beused include crops such as cereals, for example barley and wheat,cotton, oilseed rape, sunflower, maize, rice, soybeans, sugar beet,sugar cane and turf.

Crop plants can also include trees, such as fruit trees, palm trees,coconut trees or other nuts. Also included are vines such as grapes,fruit bushes, fruit plants and vegetables.

Crops are to be understood as also including those crops which have beenrendered tolerant to herbicides or classes of herbicides (e.g. ALS-,GS-, EPSPS-, PPO-, ACCase- and HPPD-inhibitors) by conventional methodsof breeding or by genetic engineering. An example of a crop that hasbeen rendered tolerant to imidazolinones, e.g. imazamox, by conventionalmethods of breeding is Clearfield® summer rape (canola). Examples ofcrops that have been rendered tolerant to herbicides by geneticengineering methods include e.g. glyphosate- and glufosinate-resistantmaize varieties commercially available under the trade namesRoundupReady® and LibertyLink®, as well as those where the crop planthas been engineered to over-express homogentisate solanesyltransferaseas taught in, for example, WO2010/029311.

Crops are also to be understood as being those which have been renderedresistant to harmful insects by genetic engineering methods, for exampleBt maize (resistant to European corn borer), Bt cotton (resistant tocotton boll weevil) and also Bt potatoes (resistant to Colorado beetle).Examples of Bt maize are the Bt 176 maize hybrids of NK® (SyngentaSeeds). The Bt toxin is a protein that is formed naturally by Bacillusthuringiensis soil bacteria. Examples of toxins, or transgenic plantsable to synthesise such toxins, are described in EP-A-451 878, EP-A-374753, WO 93/07278, WO 95/34656, WO 03/052073 and EP-A-427 529. Examplesof transgenic plants comprising one or more genes that code for aninsecticidal resistance and express one or more toxins are KnockOut®(maize), Yield Gard® (maize), NuCOTIN33B® (cotton), Bollgard® (cotton),NewLeaf® (potatoes), NatureGard® and Protexcta®. Plant crops or seedmaterial thereof can be both resistant to herbicides and, at the sametime, resistant to insect feeding (“stacked” transgenic events). Forexample, seed can have the ability to express an insecticidal Cry3protein while at the same time being tolerant to glyphosate. Crops arealso to be understood to include those which are obtained byconventional methods of breeding or genetic engineering and containso-called output traits (e.g. improved storage stability, highernutritional value and improved flavour).

Other useful plants include turf grass for example in golf-courses,lawns, parks and roadsides, or grown commercially for sod, andornamental plants such as flowers or bushes.

The compositions can be used to control unwanted plants (collectively,‘weeds’). The weeds to be controlled include both monocotyledonous (e.g.grassy) species, for example: Agrostis, Alopecurus, Avena, Brachiaria,Bromus, Cenchrus, Cyperus, Digitaria, Echinochloa, Eleusine, Lolium,Monochoria, Rottboellia, Sagittaria, Scirpus, Setaria and Sorghum; anddicotyledonous species, for example: Abutilon, Amaranthus, Ambrosia,Chenopodium, Chrysanthemum, Conyza, Galium, Ipomoea, Kochia, Nasturtium,Polygonum, Sida, Sinapis, Solanum, Stellaria, Veronica, Viola andXanthium. Weeds can also include plants which may be considered cropplants but which are growing outside a crop area (escapes), or whichgrow from seed left over from a previous planting of a different crop(volunteers). Such volunteers or escapes may be tolerant to certainother herbicides.

Preferably the weeds to be controlled and/or growth-inhibited, includemonocotyledonous weeds, more preferably grassy monocotyledonous weeds,in particular those from the following genus: Agrostis, Alopecurus,Apera, Avena, Brachiaria, Bromus, Cenchrus, Cyperus (a genus of sedges),Digitaria, Echinochloa, Eleusine, Eriochloa, Fimbristylis (a genus ofsedges), Juncus (a genus of rushes), Leptochloa, Lolium, Monochoria,Ottochloa, Panicum, Pennisetum, Phalaris, Poa, Rottboellia, Sagittaria,Scirpus (a genus of sedges), Setaria and/or Sorghum, and/or volunteercorn (volunteer maize) weeds; in particular: Alopecurus myosuroides(ALOMY, English name “blackgrass”), Apera spica-venti, Avena fatua(AVEFA, English name “wild oats”), Avena ludoviciana, Avena sterilis,Avena sativa (English name “oats” (volunteer)), Brachiaria decumbens,Brachiaria plantaginea, Brachiaria platyphylla (BRAPP), Bromus tectorum,Digitaria horizontalis, Digitaria insularis, Digitaria sanguinalis(DIGSA), Echinochloa crus-galli (English name “common barnyard grass”,ECHCG), Echinochloa oryzoides, Echinochloa colona or colonum, Eleusineindica, Eriochloa villosa (English name “woolly cupgrass”), Leptochloachinensis, Leptochloa panicoides, Lolium perenne (LOLPE, English name“perennial ryegrass”), Lolium multiflorum (LOLMU, English name “Italianryegrass”), Lolium persicum (English name “Persian darnel”), Loliumrigidum, Panicum dichotomiflorum (PANDI), Panicum miliaceum (Englishname “wild proso millet”), Phalaris minor, Phalaris paradoxa, Poa annua(POAAN, English name “annual bluegrass”), Scirpus maritimus, Scirpusjuncoides, Setaria viridis (SETVI, English name “green foxtail”),Setaria faberi (SETFA, English name “giant foxtail”), Setaria glauca,Setaria lutescens (English name “yellow foxtail”), Sorghum bicolor,and/or Sorghum halepense (English name “Johnson grass”), and/or Sorghumvulgare; and/or volunteer corn (volunteer maize) weeds.

In one embodiment, grassy monocotyledonous weeds to be controlledcomprise weeds from the genus: Agrostis, Alopecurus, Apera, Avena,Brachiaria, Bromus, Cenchrus, Digitaria, Echinochloa, Eleusine,Eriochloa, Leptochloa, Lolium, Ottochloa, Panicum, Pennisetum, Phalaris,Poa, Rottboellia, Setaria and/or Sorghum, and/or volunteer corn(volunteer maize) weeds; in particular: weeds from the genus Agrostis,Alopecurus, Apera, Avena, Brachiaria, Bromus, Cenchrus, Digitaria,Echinochloa, Eleusine, Eriochloa, Leptochloa, Lolium, Panicum, Phalaris,Poa, Rottboellia, Setaria, and/or Sorghum, and/or volunteer corn(volunteer maize) weeds.

In a further embodiment, the grassy monocotyledonous weeds are“warm-season” (warm climate) grassy weeds; in which case they preferablycomprise (e.g. are): weeds from the genus Brachiaria, Cenchrus,Digitaria, Echinochloa, Eleusine, Eriochloa, Leptochloa, Ottochloa,Panicum, Pennisetum, Phalaris, Rottboellia, Setaria and/or Sorghum,and/or volunteer corn (volunteer maize) weeds. More preferably, thegrassy monocotyledonous weeds, e.g. to be controlled and/orgrowth-inhibited, are “warm-season” (warm climate) grassy weedscomprising (e.g. being): weeds from the genus Brachiaria, Cenchrus,Digitaria, Echinochloa, Eleusine, Eriochloa, Panicum, Setaria and/orSorghum, and/or volunteer corn (volunteer maize) weeds.

In another particular embodiment the grassy monocotyledonous weeds, are“cool-season” (cool climate) grassy weeds; in which case they typicallycomprise weeds from the genus Agrostis, Alopecurus, Apera, Avena,Bromus, Lolium and/or Poa.

Various aspects and embodiments of the present invention will now beillustrated in more detail by way of example. Novel methodology andintermediates described therein are considered yet further aspects ofthe invention. It will be appreciated that modification of detail may bemade without departing from the scope of the invention.

EXAMPLES Preparation Examples

Those skilled in the art will appreciate that depending on the nature ofthe substituents X¹, X², X³, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰,R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R^(a), R^(b), R^(c), n, p, q r and s, compoundsof Formula (I) may exist in different interconvertible rotameric formsas described in, for example S. A. Richards and J. C. Hollerton,Essential Practical NMR for Organic Chemistry, John Wiley and sons(2010). For clarity, only the spectroscopic data for the major rotamericform is quoted.

Example P1: Preparation of2-bis(tert-butoxycarbonyl)amino-3-methyl-5-(5-fluoropyrid-3-yl)pyrazine(H2)

Step 1: Preparation of2-bis(tert-butoxycarbonyl)amino-3-methyl-5-(5-fluoropyrid-3-yl)pyrazine(H2)

2-Bis-(tert-butoxycarbonyl)amino-3-methyl-5-bromopyrazine (1.50 g, 3.86mmol), (5-fluoro-3-pyridyl)boronic acid (0.79 g, 5.4 mmol) and cesiumcarbonate (3.15 g, 9.7 mmol) were dissolved in a mixture of 1,4-dioxane(40 ml) and water (8 ml) and[1,1-bis(diphenylphosphino)ferrocene]-dichloropalladium(11) (160 mg,0.22 mmol) was added. The resulting mixture was heated under reflux for15 minutes, then allowed to cool, diluted with ethyl acetate (100 ml)and washed with water. The resulting organic solution was dried overmagnesium sulfate then filtered and concentrated under reduced pressureto give a light brown oil (2.1 g) which was purified by chromatographyon silica gel using a gradient of ethyl acetate in isohexane as eluentto give the title compound (1.32 g, 84% yield) as a white solid.

¹H NMR (400 MHz CDCl₃) δ 9.10; (s, 1H), 8.80; (s, 1H), 8.60; (d, 1H),8.15; (dd, 1H), 2.60; (s, 3H), 1.40; (s, 18H).

Example P2: Preparation of tert-butylN-(3-methyl-5-(5-fluoropyridin-3-yl)-pyrazin-2-yl)-N-methyl-carbamate(H19)

Step 1: Preparation of tert-butylN-(3-methyl-5-(5-fluoropyridin-3-yl)-pyrazin-2-yl)-N-methyl-carbamate(H19)

A solution of tert-butoxycarbonyl tert-butyl carbonate (610 mg, 2.8mmol) in dichloromethane (1 ml) was added dropwise to a stirred solutionof 5-(5-fluoro-3-pyridyl)-N,3-dimethyl-pyrazin-2-amine (400 mg, 1.8mmol) and 4-dimethylaminopyridine (11 mg, 0.09 mmol) in dichloromethane(15 ml) at room temperature. The resulting mixture was stirred at roomtemperature for 48 hours and then purified by chromatography on silicagel using a gradient of ethyl acetate in isohexane as eluent to givetert-butylN-(3-methyl-5-(5-fluoropyridin-3-yl)-pyrazin-2-yl)-N-methyl-carbamate(210 mg, 31% yield) as a viscous oil.

¹H NMR 400 MHz CDCl₃ δ 9.05; (s, 1H), 8.75; (s, 1H), 8.55; (s, 1H),8.10; (dd, 1H), 3.30; (s, 3H), 2.60; (s, 3H), 1.45; (s, 9H).

Example P3: Preparation of5-(5-fluoro-3-pyridyl)-3-isopropenyl-pyrazin-2-amine (Compound G14)

Step 1: Preparation of 2-amino-3-(prop-2-enyl)-5-bromopyrazine

4,4,5,5-Tetramethyl-2-(prop-2-enyl)-1,3,2-dioxaborolane (4.9 g, 27mmol), cesium carbonate (20 g, 62 mmol), water (16 ml) and[1,1′-bis(diphenylphosphino)ferrocene]-dichloropalladium(II) (960 mg,1.2 mmol) were added to a stirred solution of2-amino-3,5-dibromopyrazine (6.5 g, 25 mmol) in 1,4-dioxane (65 ml) atroom temperature. The resulting mixture was heated under reflux for 3hours, allowed to cool, and then concentrated under reduced pressure.Water was added to the resulting red residue, and the resulting mixturewas extracted with ethyl acetate. The extracts were washed with brine,dried over magnesium sulfate, then filtered and concentrated underreduced pressure to give a red oil. Purification was achieved bychromatography, first on silica gel using a gradient of ethyl acetate inisohexane as eluent, and then by mass-directed reverse phase HPLC togive the title compound (1.3 g, 24%) as a fluffy white solid.

¹H NMR (400 MHz, CDCl₃) δ 8.15; (s, 1H), 5.75; (s, 1H), 5.20; (s, 1H),5.15; (br s, 2H), 2.15; (s, 3H).

Step 2: Preparation of5-(5-fluoro-3-pyridyl)-3-isopropenyl-pyrazin-2-amine (Compound G14)

2-Amino-3-(prop-2-enyl)-5-bromopyrazine (428 mg, 2.00 mmol),(5-fluoro-3-pyridyl)boronic acid (411 mg, 2.80 mmol) and cesiumcarbonate (1.63 g, 5.00 mmol) were dissolved in a mixture of 1,4-dioxane(4.5 ml) and water (1 ml), and[1,1-bis(diphenylphosphino)ferrocene]-dichloropalladium(II) (85 mg, 0.11mmol) was added. The resulting mixture was heated under reflux for 3hours, then allowed to cool, diluted with ethyl acetate (100 ml), andthen washed with brine. The resulting organic solution was dried overmagnesium sulfate then filtered and concentrated under reduced pressureto give 2 a dark yellow liquid which began to crystallize. This waspurified by chromatography on silica gel using a gradient of ethylacetate in isohexane as eluent to give the title compound (400 mgs, 86%)as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 8.95; (s, 1H), 8.45; (d, 1H), 8.40; (s, 1H),8.00; (dd, 1H), 5.60; (s, 1H), 5.55; (s, 1H) 5.10; (br s, 2H), 2.25; (s,3H).

Example P4: Preparation of2-amino-3-(prop-2-yl)-5-(5-fluoropyrid-3-yl)pyrazine

Step 1: Preparation of2-amino-3-(prop-2-yl)-5-(5-fluoropyrid-3-yl)pyrazine (Compound G15)

5% Palladium on carbon (55% water, 10 mg, 0.09 mmol) was added to astirred solution of2-amino-3-(prop-2-enyl)-5-(5-fluoropyrid-3-yl)pyrazine (300 mg, 1.30mmol) in ethanol (10 ml) and the resulting mixture was put under anatmosphere of hydrogen (1.5 bar). After 2 hours, the reaction wasstopped and the reaction mixture was purged with nitrogen, then filteredand concentrated under reduced pressure to give the title compound (280mg, 93%) as a fluffy white solid. ¹H NMR (400 MHz, CDCl₃) δ 9.00; (s,1H), 8.45; (s, 1H), 8.35; (s, 1H), 8.00; (dd, 1H), 4.75; (br s, 2H),2.95; (m, 1H), 1.35; (d, 6H).

Example P5: Preparation of2-bis-(tert-butoxycarbonyl)amino-3,5-dibromopyrazine

Step 1: Preparation of2-bis-(tert-butoxycarbonyl)amino-3,5-dibromopyrazine

4-Dimethylaminopyridine (61 mg, 0.49 mmol) was added to a stirredsolution of 2-amino-3,5-dibromopyrazine (2.5 g, 9.8 mmol) indichloromethane (50 ml) at room temperature. A solution oftert-butoxycarbonyl tert-butyl carbonate (5.4 g, 24 mmol) indichloromethane (10 ml) was then added dropwise with stirring over 10minutes. The resulting mixture was stirred at room temperature for anhour then concentrated under reduced pressure to give2-bis-(tert-butoxycarbonyl)amino-3,5-dibromopyrazine (4.3 g, 95% yield)as a beige solid.

¹H NMR (400 MHz, CDCl₃) δ 8.45; (s, 1H), 1.40; (s, 18H).

Example P6: Preparation of2-amino-3-bromo-5-(5-fluoropyrid-3-yl)pyrazine

Step 1: Preparation of 2-amino-3-bromo-5-(5-fluoropyrid-3-yl)pyrazine

Bromine (0.20 ml, 3.8 mmol) was added dropwise to a stirred solution of2-amino-(5-fluoropyrid-3-yl)pyrazine (600 mg, 3.2 mmol) and pyridine(300 mg, 3.8 mmol) in 1,4-dioxane (30 ml) and the resulting mixture wasstirred at room temperature for one hour. The mixture was diluted withethyl acetate (100 ml) then washed with aqueous sodium bicarbonate andthen aqueous sodium metabisulfite, dried over magnesium sulfate andconcentrated under reduced pressure. The residue was purified bychromatography on silica gel using a gradient of ethyl acetate in hexaneas eluent to give 2-amino-3-bromo-5-(5-fluoropyrid-3-yl)pyrazine (160mg, 19%) as a yellow solid. ¹H NMR (400 MHz, CDCl₃)δ 8.95; (s, 1H),8.55; (s, 1H), 8.45; (s, 1H), 8.15; (dd, 1H),

Example P7: Preparation of tert-butylN-(5-bromo-3-methyl-pyrazin-2-yl)-carbamate

Step 1: Preparation of tert-butyl N-(3-methyl-pyrazin-2-yl)-carbamate

Diphenylphosphoryl azide (22.2 g, 80.5 mmol) was added to a stirredsolution of 3-methylpyrazine-2-carboxylic acid (9.0 g, 61.9 mmol) intoluene (90 ml), tert-butanol (45 ml) and triethylamine (8.18 g, 80.5mmol). The resulting mixture was heated at 90° C. for 4 hours (reactionwas observed to begin during heating, at about 65° C. internaltemperature) and then allowed to cool. The solvent was removed underreduced pressure and the residue was re-dissolved in ethyl acetate (150m). The resulting solution was washed with 2M aqueous sodium bicarbonatethen dried using a phase separation membrane, concentrated under reducedpressure and purified by chromatography on silica gel using a gradientof ethyl acetate in hexane as eluent to give tert-butylN-(3-methyl-pyrazin-2-yl)-carbamate (8.0 g, 59%) as a colourless oilwhich slowly crystallised. ¹H NMR (400 MHz, CDCl₃) δ 8.27; (d, 1H),8.23; (d, 1H), 6.85; (br s, 1H), 1.53; (s, 9H).

Step 2: Preparation of tert-butylN-(5-bromo-3-methyl-pyrazin-2-yl)-carbamate

Bromine (127 mg, 0.79 mmol) was added dropwise at room temperature to astirred solution of tert-butyl N-(3-methyl-pyrazin-2-yl)-carbamate (150mg, 0.72 mmol) and pyridine (69 mg, 0.86 mmol) in chloroform (4.5 ml).The resulting mixture was stirred at room temperature for 24 hours andthen concentrated under reduced pressure. The residue was dissolved indichloromethane (10 ml), washed with water, dried using aphase-separation membrane and purified by chromatography on silica gelusing mixtures of ethyl acetate and hexane as eluent to give tert-butylN-(5-bromo-3-methyl-pyrazin-2-yl)-carbamate as a white solid (140 mg,68%).

¹H NMR (400 MHz, CDCl₃) δ 8.30; (s, 1H), 6.65; (br s, 1H), 2.55; (s,3H), 1.55; (s, 9H).

Example P8: Preparation of 3-trifluoromethyl-2-aminopyrazine

Step 1: Preparation of tert-butylN-(3-trifluoromethylpyrazin-2-yl)-carbamate

Diphenylphosphoryl azide (3.47 g, 12.6 mmol) was added to a stirredsolution of 3-trifluoromethylpyrazine-2-carboxylic acid (1.92 g, 9.70mmol) and triethylamine (1.28 g, 12.6 mmol) in tert-butanol (9.6 ml, 100mmol) and toluene (19.2 ml). The resulting mixture was heated at 90° C.for 4 hours and then allowed to cool. It was washed with 2M aqueoussodium bicarbonate, then dried through a phase-separation filter andconcentrated under reduced pressure. The residue was purified bychromatography on silica gel using a gradient of ethyl acetate in hexaneas eluent to give tert-butyl N-(3-trifluoromethylpyrazin-2-yl)-carbamate(2.0 g) as a colourless oil which slowly crystallised to give a whitesolid. ¹H NMR (400 MHz, CDCl₃)δ 8.70; (s, 1H), 8.40; (s, 1H), 7.20; (brs, 1H), 1.55; (s, 9H).

Step 2: Preparation of 3-trifluoromethyl-2-aminopyrazine

Trifluoroacetic acid (1.1 ml, 14 mmol) was added in portions to astirred solution of tert-butylN-(3-trifluoromethylpyrazin-2-yl)-carbamate (0.92 g, ca. 3.5 mmol) in1,2-dichlorethane (9.2 ml) at room temperature. The resulting mixturewas heated under reflux for 2 hours, allowed to cool, then washed withsaturated aqueous sodium bicarbonate and dried through aphase-separation filter. Concentration under reduced pressure then gave3-trifluoromethyl-2-aminopyrazine (0.48 g) as a yellow solid. ¹H NMR(400 MHz, CDCl₃) δ 8.25; (s, 1H), 8.00; (s, 1H), 5.15; (br s, 1H).

Example P9: Preparation of tert-butylN-(3-methyl-pyrazin-2-yl)-N-methyl-carbamate

Step 1: Preparation of tert-butylN-(3-methyl-pyrazin-2-yl)-N-methyl-carbamate

A solution of tert-butyl N-(3-methyl-pyrazin-2-yl)-carbamate (1.05 g,5.0 mmol) in dry DMF was added dropwise to a stirred suspension ofsodium hydride (220 mg, 5.5 mmol) in dry DMF at room temperature (totalvolume of DMF ˜10 ml). The resulting mixture was stirred at roomtemperature for 30 minutes, then methyl iodide (3.6 g, 25 mmol) wasadded in one portion. The reaction mixture was stirred for 2 hours, thenquenched with water and extracted with ethyl acetate. The extracts werewashed with water and brine, then dried over magnesium sulfate andconcentrated under reduced pressure. The residue was purified massdirected reverse phase HPLC to give tert-butylN-(3-methyl-pyrazin-2-yl)-N-methyl-carbamate (24 mg, 2%) as an oil. ¹HNMR (400 MHz, CDCl₃) δ 7.35; (d, 1H), 7.00; (d, 1H), 3.55; (s, 3H),2.50; (s, 3H), 1.55; (s, 9H).

Example P10: Preparation of ethyl 3-difluoromethylpyrazine-2-carboxylate

Step 1: Preparation of ethyl 2-chloro-4,4-difluoroacetoacetate

Sulfuryl chloride (14.9 g, 0.11 mol) was added dropwise to ethyl4,4-difluoroacetoacetate (16.6 g, 0.1 mol) with stirring at roomtemperature. After the addition, the solution was stirred for 12 h.,then distilled to give ethyl 2-chloro-4,4-difluoroacetoacetate (17.1 g,85% yield) as a colourless liquid.

¹H NMR (400 MHz, CDCl₃) δ 11.79; (t, 1H), 5.75-6.16; (m, 0.5H), 5.49;(s, 0.5H), 4.2-4.34; (m, 2H), 1.27-1.39; (m, 3H).

Step 2: Preparation of ethyl 3-difluoromethylpyrazine-2-carboxylate

Pd/C (10 g, 5%) was added to a mixture of ethyl2-chloro-4,4-difluoroaceto-acetate (10 g, 50 mmol), sodium azide (7.8 g,120 mmol) and 1,2-ethanediamine dihydrochloride (7.98 g, 60 mmol) inwater (30 ml) and ethyl acetate (100 ml) at 30° C., and the resultingmixture was heated under reflux for 3 h. After cooling to roomtemperature, the reaction mixture was filtered and extracted with ethylacetate (3×100 ml). The combined extracts were washed with brine, driedover MgSO₄ and evaporated under reduced pressure. The residue waspurified by column chromatography on silica gel using petroleumether/ethyl acetate=3:1 as eluent to give ethyl3-difluoromethyl-pyrazine-2-carboxylate (3.0 g, 30%) as a yellow oil. ¹HNMR (400 MHz, CDCl₃) δ 8.86; (d, 2H), 7.41; (t, 1H), 4.54; (q, 2H),1.48; (t, 3H).

Further examples of the invention can be prepared similarly using themethods described above. Table 2 below, shows the structure of thesecompounds and the physical characterising data obtained using one ormore of methods as outlined below.

TABLE 2 Characterising data for compounds of Formula (I) made by themethods described above. Compound Data (400 MHz, CDCl₃) ID Structureunless stated H1

9.50 (s, 2H), 9.40 (s, 1H), 9.20 (s, 1H), 1.40 (s, 18H) H2

9.10 (s, 1H), 8.80 (s, 1H), 8.60 (d, 1H), 8.15 (dd, 1H), 2.60 (s, 3H),1.40 (s, 18H) H3

9.35 (s, 2H), 9.30 (s, 1H), 9.05 (s, 1H), 7.30 (br s, 1H), 1.60 (s, 9H)H4

9.1 (s, 1H), 9.05 (s, 1H), 8.60 (s, 1H), 8.10 (dd, 1H), 1.55 (s, 9H) H5

9.20 (s, 1H), 9.15 (s, 1H), 8.65 (s, 1H), 8.20 (dd, 1H), 1.40 (s, 18H)H6

9.10 (s, 1H), 8.60 (s, 1H), 8.50 (s, 1H), 8.10 (dd, 1H), 4.15 (s, 3H),1.40 (s, 18H) H7

9.00 (s, 1H), 8.50 (s, 1H), 8.45 (s, 1H), 7.95 (dd, 1H). 7.50 (br s,1H), 4.15 (s, 3H), 1.60 (s, 9H) H8

9.10 (s, 1H), 8.60 (s, 1H), 8.50 (s, 1H), 8.00 (dd, 1H), 7.45 (m, 2H),7.35 (m, 3H), 5.55 (s, 2H), 1.40 (s, 18H) H9

9.20 (s, 1H), 9.10 (s, 1H), 8.65 (d, 1H), 8.15 (dd, 1H), 1.50 (s, 18H)H10

9.00 (s, 2H), 8.60 (d, 1H), 8.10 (dd, 1H), 7.45 (dd, 1H), 1.60 (s, 9H)H11

9.10 (s, 1H), 8.85 (s, 1H), 8.60 (d, 1H), 8.15 (dd, 1H), 5.55 (s, 2H),2.25 (s, 3H), 1.45 (s, 18H) H12

9.05 (s, 1H), 8.70 (s, 1H), 8.55 (d, 1H), 8.05 (dd, 1H), 2.20-2.10 (m,1H), 1.45 (s, 18H), 1.30- 1.20 (m, 2H), 1.15-1.05 (m, 2H) H13

9.15 (s, 1H), 8.8 (s, 1H), 8.60 (d, 1H), 8.20 (dd, 1H), 3.25-3.15 (m,1H), 1.45 (s, 18H), 1.35 (d, 6H) H14

9.10 (s, 1H), 8.75 (s, 1H), 8.60 (d, 1H), 8.10 (dd, 1H), 6.30 (s, 1H),2.25 (s, 3H), 2.05 (s, 3H), 1.40 (s, 18H) H15

9.10 (s, 1H), 8.80 (s, 1H), 8.55 (d, 1H), 8.15 (dd, 1H), 6.35 (t, 1H),2.60-2.50 (m, 2H), 2.30- 2.20 (m, 2H), 1.85-1.75 (m, 2H), 1.75-1.65 (m,2H), 1.45 (s, 18H) H16

9.10 (s, 1H), 8.90 (s, 1H), 8.60 (d, 1H), 8.15 (dd, 1H), 1.45 (s, 18H)H17

9.00 (s, 1H), 8.70 (s, 1H), 8.50 (s, 1H), 8.05 (dd, 1H), 6.80 (br s,1H), 2.60 (s, 3H), 1.55 (s, 9H) H18

9.10 (s, 1H), 8.95 (s, 1H), 8.60 (s, 1H), 8.15 (dd, 1H), 5.25 (s, 2H),1.55 (s, 9H), 1.45 (s, 18H) H19

9.05 (s, 1H), 8.75 (s, 1H), 8.55 (s, 1H), 8.10 (dd, 1H), 3.30 (s, 3H),2.60 (s, 3H), 1.45 (s, 9H) H20

9.15 (s, 1H), 8.85 (s, 1H), 8.60 (d, 1H), 8.20 (dd, 1H), 6.90 (dd, 1H),6.70 (dd, 1H), 5.75 (dd, 1H), 1.40 (s, 18H) H21

9.10 (s, 1H), 8.80 (s, 1H), 8.55 (d, 1H), 8.15 (dd, 1H), 2.85 (q, 2H),1.45 (s, 18H), 1.35 (t, 3H) H22

8.95 (s, 1H), 8.55 (s, 1H), 8.45 (d, 1H), 8.00 (dd, 1H), 5.35 (br s,2H), 1.50 (s, 9H) H23

9.35 (s, 2H), 9.25 (s, 1H), 8.65 (s, 1H), 6.90 (br s, 1H), 2.65 (s, 3H),1.55 (s, 9H) H24

9.05 (s, 1H), 8.60 (s, 1H), 8.55 (d, 1H), 8.00 (dd, 1H), 6.90 (br s,1H), 2.70 (s, 3H), 1.55 (s, 9H) H25

8.95 (s, 1H), 8.57-8.55 (m, 2H), 8.15 (t, 1H), 6.85 (br s, 1H), 2.75 (s,3H), 2.60 (s, 3H), 1.60 (s, 9H) H26

9.12-9.10 (m, 2H), 8.65 (d, 1H), 8.20 (dd, 1H), 4.00 (s, 3H), 1.45 (s,18H) H27

9.17-9.14 (m, 2H), 8.65 (d, 1H), 8.20 (dd, 1H), 6.78 (t, 1H), 1.45 (s,18H) H28

9.05 (s, 1H), 9.00 (s, 1H), 8.60 (d, 1H), 8.05 (dd, 1H), 7.45 (br s,1H), 6.88 (t, 1H), 1.55 (s, 9H) H29

9.10 (s, 1H), 8.90 (s, 1H), 8.60 (d, 1H), 8.15 (dd, 1H), 3.50. (s, 1H),1.45 (s, 18H) H30

9.32-9.30 (m, 3H), 9.00 (s, 1H), 7.45 (brs , 1H), 6.90 (t, 1H), 1.60 (s,9H) H31

9.45 (s, 2H), 9.40 (s, 1H), 9.10 (s, 1H), 6.80 (t, 1H), 1.45 (s, 18H)H32

9.10 (s, 1H), 8.80 (s, 1H), 8.60 (d, 1H), 8.20 (dd, 1H), 1.45 (s, 18H),0.30 (s, 9H)

Physical Characterisation

Compounds of the invention were characterised using one or more of thefollowing methods.

NMR

NMR spectra contained herein were recorded on either a 400 MHz BrukerAVANCE III HD equipped with a Bruker SMART probe or a 500 MHz BrukerAVANCE III equipped with a Bruker Prodigy probe. Chemical shifts areexpressed as ppm downfield from TMS, with an internal reference ofeither TMS or the residual solvent signals. The following multiplicitiesare used to describe the peaks: s=singlet, d=doublet, t=triplet,dd=double doublet, m=multiplet. Additionally br. is used to describe abroad signal and app. is used to describe an apparent multiplicity.

LCMS

LCMS data contained herein consists of the molecular ion [MH+] and theretention time (tr) of the peak recorded on the chromatogram. Thefollowing instruments, methods and conditions were used to obtain LCMSdata:

Method A

Instrumentation: Waters Acquity UPLC-MS using a Sample Organizer withSample Manager FTN, H-Class QSM, Column Manager, 2×Column Manager Aux,Photodiode Array (Wavelength range (nm): 210 to 400, ELSD and SQD 2equipped with a Waters HSS T3 C18 column (column length 30 mm, internaldiameter of column 2.1 mm, particle size 1.8 micron).

Ionisation method: Electrospray positive and negative: Capillary (kV)3.00, Cone (V) 30.00, Source Temperature (° C.) 500, Cone Gas Flow(L/Hr.) 10, Desolvation Gas Flow (L/Hr.) 1000. Mass range (Da): positive95 to 800, negative 115 to 800.

The analysis was conducted using a two minute run time, according to thefollowing gradient table at 40° C.:

Time (mins) Solvent A (%) Solvent B (%) Flow (ml/mn) 0.00 95.0 5.0 0.71.75 0.0 100 0.7 1.76 0.0 100 0.7 2.0 0.0 5.0 0.7 2.01 95.0 5.0 0.7 2.1195.0 5.0 0.7 Solvent A: H₂O with 0.05% TFA Solvent B: CH₃CN with 0.05%TFA

Method B (2 min Method)

Instrumentation: Either (a) Waters Acquity UPLC system with Waters SQD2single-quad MS detector, Photodiode Array Detector (AbsorbanceWavelength: 254 nm, 10 pts/sec, Time Constant: 0.2000 sec), ChargedAerosol Detector (Corona) and Waters CTC 2770 auto-sampler unit(injection volume: 2 microliters, 1 min seal wash); or (b) WatersAcquity UPLC system with Waters QDa single-quad MS detector, PhotodiodeArray Detector (Absorbance Wavelength: 254 nm, 10 pts/sec, TimeConstant: 0.2000 sec), Charged Aerosol Detector (Corona) and Waters CTC2770 auto-sampler unit (injection volume: 2 microliters, 1 min sealwash).

LC-Method

Phenomenex ‘Kinetex C18 100A’ column (50 mm×4.6 mm, particle size 2.6micron), Flow rate: 2 mL/min at 313K (40 Celsius), Gradient (Solvent A:H₂O with 0.1% Formic Acid; Solvent B: Acetonitrile with 0.1% FormicAcid):

The analysis was conducted using a two minute run time, according to thefollowing gradient table at 40° C.

Time (mins) Solvent A (%) Solvent B (%) Flow (ml/mn) Initial 70.0 30.02.000 1.20 10.0 90.0 2.000 1.70 10.0 90.0 2.000 1.80 70.0 30.0 2.0002.00 70.0 30.0 2.000 2.20 70.0 30.0 2.000

Method C (1 min Method)

Instrumentation: Either (a) Waters Acquity UPLC system with Waters SQD2single-quad MS detector, Photodiode Array Detector (AbsorbanceWavelength: 254 nm, 10 pts/sec, Time Constant: 0.2000 sec), ChargedAerosol Detector (Corona) and Waters CTC 2770 auto-sampler unit(injection volume: 2 microliters, 1 min seal wash); or (b) WatersAcquity UPLC system with Waters QDa single-quad MS detector, PhotodiodeArray Detector (Absorbance Wavelength: 254 nm, 10 pts/sec, TimeConstant: 0.2000 sec), Charged Aerosol Detector (Corona) and Waters CTC2770 auto-sampler unit (injection volume: 2 microliters, 1 min sealwash).

LC-Method

Phenomenex ‘Kinetex C18 100A’ column (50 mm×4.6 mm, particle size 2.6micron), Flow rate: 2 mL/min at 313K (40 Celsius),

Gradient (Solvent A: H₂O with 0.1% Formic Acid; Solvent B: Acetonitrilewith 0.1% Formic Acid):

The analysis was conducted using a one minute run time, according to thefollowing gradient table at 40° C.

Time (mins) Solvent A (%) Solvent B (%) Flow (ml/mn) Initial 60.0 40.02.000 0.80 0.0 100.0 2.000 0.95 0.0 100.0 2.000 1.00 60.0 40.0 2.0001.10 60.0 40.0 2.000 1.25 60.0 40.0 2.000

Biologicial Examples B1 Pre-Emergence Herbicidal Activity

Seeds of a variety of test species were sown in standard soil in pots:Triticum aestivium (TRZAW), Avena fatua (AVEFA), Alopecurus myosuroides(ALOMY), Echinochloa crus-galli (ECHCG), Lolium perenne (LOLPE), andSetaria faberi (SETFA). After cultivation for one day (pre-emergence)under controlled conditions in a glasshouse (at 24/16° C., day/night; 14hours light; 65% humidity), the plants were sprayed with an aqueousspray solution derived from the formulation of the technical activeingredient in acetone/water (50:50) solution containing 0.5% Tween 20(polyoxyethelyene sorbitan monolaurate, CAS RN 9005-64-5). The testplants were then grown in a glasshouse under controlled conditions (at24/16° C., day/night; 14 hours light; 65% humidity) and watered twicedaily. After 13 days, the test was evaluated (5=total damage to plant;0=no damage to plant). Results are shown in Table B1.

TABLE B1 Control of weed species by compounds of Formula (I) afterpre-emergence application Com- pound Rate ID (g/ha) ECHCG LOLPE SETFAAVEFA ALOMY TRAZW H1 1000 4 1 4 2 0 0 H2 1000 4 2 5 2 0 0 H4 1000 4 1 53 0 0 H5 1000 5 1 5 2 0 0 H6 1000 3 0 4 1 0 1 H7 1000 3 0 5 1 0 0 H81000 1 1 2 0 0 0 H9 1000 2 1 5 1 0 0 H10 1000 2 0 4 0 0 0 H11 1000 3 2 40 1 0 H12 1000 1 0 4 0 0 0 H13 1000 1 0 4 0 0 0 H14 1000 2 2 3 0 0 0 H151000 0 0 0 0 0 0 H16 1000 1 0 1 0 0 0 H17 1000 4 3 4 2 0 0 H18 1000 3 14 0 0 0 H19 1000 4 1 5 2 0 0 H20 1000 2 1 4 2 0 1 H21 1000 1 5 5 2 0 0H22 1000 0 0 0 0 0 0 H23 1000 2 0 4 1 0 0 H24 1000 2 1 5 2 0 0 H25 250 00 0 0 0 0 H26 1000 0 0 5 0 0 0 H27 1000 4 0 4 2 0 0 H28 1000 2 0 4 2 3 0H29 1000 0 0 0 0 0 0 H30 1000 3 1 4 0 0 1 H31 1000 2 0 2 1 2 0

Compounds that score 4 or 5 on one or more plant species areparticularly preferred.

B2 Post-Emergence Herbicidal Activity

Seeds of a variety of test species were sown in standard soil in pots:Triticum aestivium (TRZAW), Avena fatua (AVEFA), Alopecurus myosuroides(ALOMY), Echinochloa crus-galli (ECHCG), Lolium perenne (LOLPE), andSetaria faberi (SETFA). After 8 days cultivation (post-emergence) undercontrolled conditions in a glasshouse (at 24/16° C., day/night; 14 hourslight; 65% humidity), the plants were sprayed with an aqueous spraysolution derived from the formulation of the technical active ingredientin acetone/water (50:50) solution containing 0.5% Tween 20(polyoxyethelyene sorbitan monolaurate, CAS RN 9005-64-5). The testplants were then grown in a glasshouse under controlled conditions (at24/16° C., day/night; 14 hours light; 65% humidity) and watered twicedaily. After 13 days, the test was evaluated (5=total damage to plant;0=no damage to plant). Results are shown in Table B2.

TABLE B2 Control of weed species by compound of Formula (I) afterpost-emergence application Com- pound Rate ID (g/ha) ECHCG LOLPE SETFAAVEFA ALOMY TRAZW H1 1000 5 3 5 4 0 0 H2 1000 5 2 5 3 0 0 H4 1000 5 2 53 0 1 H5 1000 5 2 5 3 0 1 H6 1000 3 1 4 2 0 1 H7 1000 5 2 5 3 0 1 H81000 1 0 1 1 0 0 H9 1000 3 1 5 3 0 0 H10 1000 2 1 5 1 0 0 H11 1000 3 2 52 0 0 H12 1000 3 2 5 2 0 0 H13 1000 2 1 5 1 0 1 H14 1000 2 1 4 1 0 0 H151000 0 0 2 1 0 0 H16 1000 1 2 3 1 0 0 H17 1000 4 3 NT* 3 2 0 H18 1000 41 3 1 0 0 H19 1000 4 2 5 3 0 0 H20 1000 4 3 5 2 0 1 H21 1000 4 4 5 4 1 1H22 1000 1 1 2 1 0 0 H23 1000 4 2 5 3 1 1 H24 1000 4 2 5 3 0 0 H25 250 11 1 1 0 0 H26 1000 3 0 5 1 0 1 H27 1000 5 4 5 4 0 1 H28 1000 5 3 5 4 0 0H29 1000 1 1 1 0 0 1 H30 1000 4 2 4 3 1 1 H31 1000 5 2 5 3 1 1 *NT = nottested

Compounds which score 4 or 5 on one or more plant species areparticularly preferred.

The invention claimed is:
 1. A compound of Formula (I)

or a salt thereof, wherein, X¹ is N or CR¹; R¹ is selected from thegroup consisting of hydrogen, halogen, cyano, C₁-C₆alkyl,C₃-C₆cycloalkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₁-C₆alkoxy,—C(O)OC₁-C₆alkyl, —S(O)_(p)C₁-C₆alkyl, NR⁶R⁷, C₁-C₆haloalkoxy andC₁-C₆haloalkyl; R² is selected from the group consisting of halogen,cyano, nitro, C₁-C₆alkyl, C₁-C₆haloalkyl, C₂-C₆alkenyl, C₂-C₆alkynyl,trimethylsilylC₂-C₆alkynyl-, C₃-C₆cycloalkyl, C₅-C₆cycloalkenyl,—C(O)OC₁-C₆alkyl, —S(O)_(p)(C₁-C₆alkyl), C₁-C₆alkoxy, C₁-C₆haloalkoxy,—(CR^(a)R^(b))R¹⁵, phenyl and benzyloxy; R¹⁵ is hydroxy, —C(O)OR^(c),—OC(O)R¹⁵, —C₃-C₆cycloalkyl, or an aryl, -aryloxy, -heteroaryl,-heteroaryloxy or -heterocyclyl ring, wherein said ring is optionallysubstituted by 1 to 3 independent R⁸; R³ is —C(O)X²R¹²; X² is O or NR¹⁰;R⁴ is selected from the group consisting of hydrogen, C₁-C₆alkyl,C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy, C₃-C₆cycloalkyl,C₃-C₆alkenyl, C₃-C₆alkynyl, —C(O)R⁹—(CR^(a)R^(b))_(q)R⁵, —C(O)X³R¹³; or,when X² is O, R¹² is selected from the group consisting of C₁-C₆alkyl,C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl, C_(r)alkoxyC_(s)haloalkyl,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹, or R⁴ and R¹² together with the heteroatoms towhich they are joined form a 5-7 membered ring system optionallycontaining 1 additional heteroatom selected from S, O and N, whereinwhen said additional heteroatom is sulphur it is in the form S(O)_(p);when X² is NR¹⁰, R¹² is selected from the group consisting of hydrogen,C₁-C₆alkyl, C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹; or R¹⁰ and R¹² together with the nitrogen atom towhich they are both joined, can form a 5-, 6-, or 7-memberered ring,optionally containing 1 to 3 additional heteroatoms each independentlyselected from O, N or S, wherein when said ring contains a ring sulphur,said ring sulphur is in the form S(O)_(p); or R⁴ and R¹⁰ together withthe atoms to which they are joined form a 5-7 membered ring systemoptionally comprising from 1 or 2 additional heteroatoms independentlyselected from S, O and N and wherein when said ring system contains aring sulphur, said ring sulphur is in the form S(O)_(p), or, R¹⁰ isindependently selected from the group consisting of hydrogen,C₁-C₆alkyl, C₃-C₆ cycloalkyl; when R⁴ is —C(O)X³R¹³, X³ is O or NR¹⁴;when X³ is O, R¹³ is selected from the group consisting of C₁-C₆alkyl,C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl, C_(r)alkoxyC_(s)haloalkyl,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹, or R³ and R¹³ together with the heteroatoms towhich they are joined form a 5-7 membered ring system optionallycontaining 1 additional heteroatom selected from S, O and N, whereinwhen said additional heteroatom is sulphur it is in the form S(O)_(p);when X³ is NR¹⁴, R¹³ is selected from the group consisting of hydrogen,C₁-C₆alkyl, C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy,C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, and—(CR^(a)R^(b))_(q)R¹¹; or R¹⁴ and R¹³ together with the nitrogen atom towhich they are both joined, can form a 5-, 6-, or 7-memberered ring,optionally containing 1 or 2 additional heteroatoms each independentlyselected from O, N or S, wherein when said ring contains a ring sulphur,said ring sulphur is in the form S(O)_(p); R^(a) is hydrogen or C₁-C₂alkyl; R^(b) is hydrogen or C₁-C₂ alkyl; R^(c) is hydrogen orC₁-C₄alkyl; R⁵ is cyano, —C(O)OC₁-C₆alkyl, —C₃-C₆cycloalkyl, -aryl orheteroaryl wherein said aryl and heteroaryl are optionally substitutedby 1 to 3 independent R⁸; R⁶ and R⁷ are independently selected from thegroup consisting of hydrogen, C₁-C₆alkyl, and —C(O)OC₁-C₄alkyl; each R⁸is independently selected from the group consisting of halogen,C₁-C₆alkyl and C₁-C₆alkoxy-, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy-, cyanoand S(O)_(p)(C₁-C₆alkyl); R⁹ is selected from the group consisting ofhydrogen, C₁-C₆alkyl, C₁-C₆alkoxy, C₁-C₆haloalkyl, C₁-C₆haloalkoxy,C₂-C₆alkenyl, C₂-C₆alkynyl, and —(CR^(a)R^(b))_(q)R¹¹; R¹¹ is cyano,—C₃-C₆cycloalkyl, or an -aryl, -heteroaryl or -heterocyclyl ring,wherein said ring is optionally substituted by 1 to 3 independent R⁸,and wherein when said ring contains a ring sulphur, said ring sulphur isin the form S(O)_(p); n is 0 or 1; p is 0, 1, or 2; q is 0, 1, 2, 3, 4,5 or 6; r is 1, 2, 3, 4, or 5, s is 1, 2, 3, 4, or 5, and the sum of r+sis less than or equal to
 6. 2. The compound of Formula (I) according toclaim 1, wherein X¹ is N.
 3. The compound of Formula (I) according toclaim 1, wherein X¹ is CR¹ and R¹ is selected from the group consistingof cyano, halogen, C₁-C₆alkoxy, C₁-C₆haloalkoxy, C₁-C₆haloalkyl, and—S(O)_(p)C₁-C₆alkyl.
 4. The compound of Formula (I) according to claim1, wherein R² is selected from the group consisting of halogen, cyano,C₁-C₄alkyl, C₃-C₆cycloalkyl, C₁-C₄alkoxy, C₁-C₄haloalkyl,C₁-C₄thioalkyl, C₂-C₄alkenyl, C₅-C₆cycloalkenyl, C₂-C₄alkynyl,trimethylsilylC₂-C₄alkynyl-, —C(O)OC₁-C₄alkyl, —(CR^(a)R^(b))_(q)R¹⁵,phenyl, and benzyloxy.
 5. The compound of Formula (I) according to claim1, wherein X² is O.
 6. The compound of Formula (I) according to claim 5,wherein R¹² is selected from the group consisting of hydrogen,C₁-C₆alkyl, C_(r)alkoxyC_(s)alkyl, C₁-C₆haloalkyl,C_(r)alkoxyC_(s)haloalkyl, C_(r)alkylthioC_(s)alkyl, C₂-C₆alkenyl,C₂-C₆alkynyl, and —(CR^(a)R^(b))_(q)R¹¹.
 7. The compound of formula (I)according to claim 1, wherein X² is NR¹⁰.
 8. The compound of formula (I)according to claim 7, wherein R¹⁰ is hydrogen or C₁-C₆alkyl.
 9. Thecompound of formula (I) according to claim 7, wherein R¹⁰ is hydrogen orC₁-C₆alkyl, and R¹² is C₁-C₄alkyl, C₁-C₃alkoxy, —(CH₂)₃SCH₃,C₁-C₃haloalkyl, C₃-C₆alkynyl, or (CR^(a)R^(b))_(q)R¹¹.
 10. The compoundof Formula (I) according to claim 1, wherein R⁴ is selected from thegroup consisting of hydrogen, methyl, ethyl, allyl, but-2-yn-1-yl,C(O)R⁹ where R⁹ is C₁-C₆alkoxy, and —(CH₂)_(q)R⁵ wherein q is 1 and R⁵is selected from the group consisting of c-propyl, —CO₂methyl, andphenyl optionally substituted by 1-2 groups R⁸, wherein each R⁸ isindependently C₁-C₃alkyl or halogen.
 11. The compound of Formula (I)according to claim 10, wherein R⁹ is C₁-C₆alkoxy.
 12. A herbicidalcomposition comprising a compound according to claim 1 and anagriculturally acceptable formulation adjuvant.
 13. The herbicidalcomposition according to claim 12, further comprising at least oneadditional pesticide.
 14. The herbicidal composition according to claim13, wherein the additional pesticide is a herbicide or herbicidesafener.
 15. A method of controlling weeds at a locus comprisingapplication to the locus of a weed controlling amount of a compound offormula (I) according to claim 1.